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Review  |  Dermatol Pract Concept 2015;5(2):1 1

DERMATOLOGY PRACTICAL & CONCEPTUAL
www.derm101.com

1 Dermatology Specialists, Bridgeton, Missouri, USA
Citation: Hookerman BJ. Dermatopathology: An abridged 
compendium of words. A discussion of them and opinions about 
them. Part 8 (P-S). Dermatol Pract Concept 2015;5(2):1. doi: 
10.5826/dpc.0502a01

Copyright: ©2015 Hookerman. This is an open-access article 
distributed under the terms of the Creative Commons Attribution 
License, which permits unrestricted use, distribution, and 
reproduction in any medium, provided the original author and 
source are credited.

Corresponding author: Bruce J. Hookerman, MD, 12105 Bridgeton 
Square Drive, St. Louis, MO 63044, USA. Email: bjhookerman@
aol.com

The compendium (Part 8)

– P –
PAGET CELL: specific for mammary Paget’s disease and 
extramammary Paget’s disease, is typified by a large, round, 

or plump oval nucleus and pale-staining cytoplasm, the lat-

ter being more abundant in extramammary Paget’s disease 

because there it is replete with acid mucopolysaccharides that 

are demonstrable by staining with hematoxylin and eosin 

and better yet with stains specialized for them. Paget cells of 

mammary Paget’s disease and extramammary Paget’s disease 

have several attributes in common, but they are dissimilar, just 

as are mammary Paget’s disease and extramammary Paget’s 

diseases themselves, despite the fact that they share the word 

“mammary” and the name Paget’s disease.”

PAGET PATTERN: is scatter of cells constituent of mammary 
Paget’s disease and extramammary Paget’s disease throughout 

an epithelium, usually epidermal but also adnexal.

PAGETOID CELL: is one that resembles the cell constituent 
of Paget’s disease especially of extramammary Paget’s disease 

by having a large roundish nucleus and abundant pale cyto-

plasm. It is found, for example, in some lesions of melanoma 

and of Bowen’s disease.

PAGETOID MELANOCYTE: an abnormal melanocyte 
with abundant pale cytoplasm, but less abundant than in a 

ballooned melanocyte and such cells may be dispersed singly 

or in nests within the epidermis. They resemble the pale 

cells found within the epidermis of lesions of mammary and 

extramammary Paget’s disease. Pagetoid melanocytes may 

contain dusty particles of melanin. If they do not, reliable 

differentiation from true Paget cells depends on histochemi-

cal techniques. Paget cells are DOPA negative and contain 

either neutral mucopolysaccharides (in mammary disease) 

or sialomucin (in extramammary disease). Pagetoid mela-

nocytes are DOPA-positive and do not contain mucin. They 

are usually seen in melanomas, especially those on the trunk 

and proximal parts of the extremities, but also are found in 

some melanocytic nevi, especially combined melanocytic nevi.

PAGETOID MELANOCYTIC PROLIFERATION: a phrase 
coined by Wallace H. Clark, Jr. and advocated by a panel of 

dermatopathologists appointed by the National Institutes 

of Health to forge definitions of terms employed in the 

language of melanocytic neoplasia, they being published in 

1992. In brief “pagetoid melanocytic proliferation” was yet 

another attempt at evasion from a diagnosis by microscopy 

conventional of “melanoma in situ” and, like all the others, 

has faded into oblivion.

PAGETOID PATTERN: is descriptive of scatter of cells 
proliferative throughout an epithelium, usually epidermal 

but also adnexal, in the manner, that it is seen in mammary 

Paget’s disease and extramammary Paget’s disease, e.g., in 

melanoma, Bowen’s disease, and mycosis fungoides. Thus 

pagetoid cells may or may not appear in pagetoid pattern in 

a given histopathologic section (i.e., melanoma).

PALE CELL: is one, whose cytoplasm is deficient in intensity 
of color, i.e., pallid, as seen in some examples of apocrine 

(pale-cell) hidradenoma, in pale cell acanthoma, and in pale 

cell acanthosis. (SEE CLEAR CELLS)

Dermatopathology: An abridged compendium 
of words. A discussion of them and opinions 

about them. Part 8 (P-S)
Bruce J. Hookerman1



2 Review  |  Dermatol Pract Concept 2015;5(2):1

PAPILLOMA: refers to nipple-like projections above the skin 

surface as a consequence of extensions outward of dermal 

papillae (papillomatosis) that may or may not be covered 

by thickened epidermis. Cutaneous papillomas include those 

that have fibrous cores, i.e., fibroepithelial papillomas, and 

those that consist mostly of papillated epithelium, i.e., con-

dylomata. The term “verrucous” sometimes is used synony-

mously with papillomatous, but the tips of dermal papillae in 

verrucous lesions tend to be pointed (digitated), i.e., verruca 

vulgaris, rather than rounded (papillomatous), i.e., condy-

loma acuminatum.

PAPILLOMATOUS: refers to a nipple-like projections above 

the skin surface seemingly as a consequence of extensions 

outward of dermal papillae (papillomatous) that may or may 

not be covered by thickened epidermis. Cutaneous papillomas 

include those that have a fibrous core, e.g., fibroepithelial 

papillomas and those that consist mostly of epithelium papil-

late, e.g., condylomata acuminata. The term “verrucous” 

sometimes is used synonymously with papillomatous, but 

the tip of epidermal excrescences in lesions verrucous often 

are pointed (digitated), i.e., verrucae vulgares, rather than 

rounded (papillomatous), i.e., condyloma acuminatum.

PAPULE: a small, i.e., up to 1.0 cm, slightly raised, solid 

or cystic lesion. A papule may be formed by abnormalities 

mostly of surface epidermis, as in a plane wart, by changes 

mostly in infundibular epidermis and in the dermis adjacent 

to it, as in lichen planopilaris, by ones mostly in the papillary 

dermis, as in a lesion of lichen nitidus, by findings mostly in 

the reticular dermis, as in a small infundibular cyst (a milium), 

or by aberrations of both epidermis and dermis together, as in 

a lesion of conventional lichen planus. The surface of a papule 

maybe flat (i.e. lichenoid, as in lichen planus) as it presents 

itself usually, hemispherical, as in lichen nitidus, or conical, 

as in a variety of spongiotic dermatitides, such as allergic 

contact dermatitis. Papules may be either smooth, like that of 

an incipient lesion of guttate psoriasis, or scaly, as in a later 

lesion of guttate psoriasis in which the original cornified layer 

that covers mounds of parakeratosis has been shed.

The time-honored litany of “papulosquamous diseases” 

should be abandoned because the diseases said to constitute 

that assemblage are unrelated wholly to one another, i.e., 

seborrheic dermatitis and secondary syphilis, “guttate para-

psoriasis” (one pattern of mycosis fungoides) and psoriasis, 

lichen planus and pityriasis rosea. Moreover, many conditions 

that are typified by scaly papules are not included in the so 

called papulosquamous group, among those being a particu-

lar presentation of sarcoidosis on a leg, one manifestation 

of Grover’s disease (the Darier type), and some examples of 

dermatophytosis.

PALE-CELL ACANTHOSIS: refers to a specific histopatho-
logic pattern within a thickened epidermis in which there are 

discrete zones of large pale-staining keratinocytes separated 

widely from one another by prominent intercellular spaces 

traversed by elongated bridges. Neutrophils usually pepper 

the foci of pale keratocytes. In short, the changes of pale-cell 

acanthosis are identical to those that constitute the benign 

neoplasm named pale-cell acanthoma. (SEE CLEAR CELLS)

PALISADE: refers to the appearance of cells aligned in the 
fashion of stakes like those that form a line of defense in a 

fortification, i.e., columnar cells at the periphery of an outer 

sheath at the bulb of a normal hair follicle; germinative cells 

at the periphery of a “follicular” germ in an embryo, of aggre-

gations of cells in a trichoblastoma, and of aggregations of 

cells in trichoblastic (basal cell) carcinoma; histiocytes around 

a zone of mucin and of degenerated collagen in granuloma 

annulare and around a zone of fibrin in rheumatoid nodule, 

and nuclei of Schwann cells apposed directly to one another 

at the distal end of their respective cytoplasm in Verocay bod-

ies of schwannomas.

PANNICULITIS: an inflammatory disease in which the 
infiltrate of inflammatory cells is present in the panniculus 

adiposa (subcutaneous fat). For purposes of facilitating diag-

nosis by conventional microscopy of panniculitis, the process 

is divided arbitrarily as “septal” and “lobular,” depending on 

whether the infiltrate of inflammatory cells, as seen at scan-

ning magnification, mostly is in fibrous septa or mostly in fat 

lobules. Sometimes, septa and lobules are affected equally. 

There can be significant overlap.

PAPILLARY: means shaped like a nipple. The root “pap” 
appears in several names for cutaneous structures, i.e., pap-

illary dermis, dermal papilla, follicular papilla, papilloma, 

papillomatosis, papillations, and papillated. Nipple-like 

projections above the skin surface may be seen as an affect 

of proliferations of keratocytes as in condylomata acuminata 

and of extension outward of papillary dermis, i.e., papilloma-

tosis, as in acanthosis nigricans. Papillomatous and papillated 

are synonymous with papillary.

PAPILLARY DERMIS: refers to the uppermost portion of 
the dermis that has nipple-like projections into hollows in 

the underside of the epidermis. Collagen in the papillary 

dermis is seen as delicate fibrils in contrast to collagen in the 

reticular dermis, which is arranged in bundles. Capillaries in 

the papillary dermis emerge from venules that are situated in 

the uppermost portion of the reticular dermis and, for that 

reason, this plexus is also known as the subpapillary plexus.

PAPILLATIONS: are projections above the skin surface or 
into the lumen of a structure tubular or cystic and that may 

be seen as an effect of proliferations of epithelial cells alone 

or of fibrous core protrusive covered by epithelial cells.



Review  |  Dermatol Pract Concept 2015;5(2):1 3

wrongly to interpret an inflammatory disease as a lymphoma. 

In fact, there, is no need for the term parapsoriasis because 

the actual diagnoses are either Mucha-Habermann disease or 

mycosis fungoides or whatever other named disease is being 

considered.

PARAPSORIASIS EN PLAQUES: is a synonym for one 
expression of the early patch stage of mycosis fungoides. It 

is a term that is no longer relevant. (SEE PARAPSORIASIS)

PART OF A FOLLICLE: is a term applied to each of two units 
that constitute each of the two segments of a follicle. Each 

part has its own morphologic appearance, and each is delim-

ited by distinct boundaries. From bottom up, the lower tran-

sient segment of a follicle is composed of two parts, namely, 

bulb and stem, and the upper permanent segment of isthmus.

PAS: is based on an acronym for periodic acid-Schiff. Periodic 
acid in a stain is used as an oxidizing agent. A solution of 

Schiff reagent consists of basic fuchsine, hydrochloric acid, 

and sodium bisulfate and serves as the actual stain. PAS stain 

is used to detect carbohydrates and mucoproteins. When 

material stained by PAS is removed by diastase, that material 

must be glycogen.

PATCH: a broad, i.e., more than 1.0 cm, flat lesion. A macule, 
in contrast to a patch, is a flat lesion less than 1.0 cm in great-

est diameter. A patch may begin as a macule, as in vitiligo, or 

it may appear as a patch from the outset, such as a café au 

lait “spot.” Alterations histopathologic that are responsible 

for patches are the same as those for macules. A café au lait 

spot of neurofibromatosis results from an increase in melanin 

within the epidermis, a purple patch of an ecchymosis from 

extravasation of erythrocytes in the dermis, and a reddish 

patch of a blush or of a sunburn from erythrocytes congested 

within dilated blood vessels of the superficial plexus.

PATTERN: refers to a design or arrangement of figures 
or structures. In clinical dermatology, pattern includes dis-

tribution of lesions, arrangement of lesions, configuration 

of lesions, and outline of individual lesions themselves. In 

dermatopathology, pattern pertains mostly to distribution 

and arrangement of infiltrates of inflammatory cells and to 

silhouettes formed by neoplastic cells. They are the vehicles 

used to arrive at the correct diagnoses with specificity.

In dermatopathology pattern usually refers to patterns of 

inflammatory cells. However, the concept of pattern is more 

far reaching. The following discussion illustrates this. Rather 

than conceive of distinctive expressions of pathologic pro-

cesses as specific diseases, it may be more accurate, and, 

therefore, more illuminating, to think of them as “patterns 

of disease.” For example, dermatologists understand, full 

well, that conditions like erythema multiforme, erythema 

nodosum, and leukocytoclastic vasculitis represent repeatable 

PAPULOVESICLE: describes a combination of a papule and 
a vesicle.

PARAKERATOSIS: retention of nuclei in cornified cells. It 
results either from acceleration in epidermopoiesis (i.e., in 

psoriasis) or from faulty maturation of keratocytes (i.e., in 

Bowen’s disease). Within the epidermal cornified layer of 

different inflammatory diseases, parakeratosis may occur in 

mounds, as in guttate psoriasis, in alternation with orthokera-

tosis, both vertically and horizontally, as in pityriasis rubra 

pilaris, in broad zones of confluence, as in plaques of fully 

developed psoriasis, and in mounds that also contain serum, 

as in seborrheic dermatitis. Parakeratosis may be observed in 

neoplasms such as solar keratosis (a superficial squamous-cell 

carcinoma of one type), in which the epidermis displays broad 

columns of parakeratosis that alternate at intervals with thin 

columns of orthokeratosis, the latter being stationed at sites 

of acrosyringia and infundibula (so-called acrotrichia), and 

in a much thicker squamous-cell carcinoma, where whorls of 

parakeratosis within aggregations of neoplastic keratocytes 

are referred to colloquially as “horn pearls.” One expression 

of epidermal nevus, i.e., inflammatory linear epidermal nevus, 

is typified by stubby, straight columns of parakeratosis, in 

contrast to the situation in disseminated superficial actinic 

porokeratosis, in which thin columns of parakeratosis tilt 

toward the center of the lesion.

PARAPSORIASIS: a term given to five cutaneous conditions, 
namely, parapsoriasis (pityriasis) lichenoides et varioliformis 

acuta, parapsoriasis (pityriasis) lichenoides chronica, para-

psoriasis guttate, parapsoriasis en plaques, and parapsoriasis 

variegate. Since Brocq’s seminal article in 1902 devoted exclu-

sively to parapsoriasis, those five conditions have been held to 

be vaguely related to one another in a “parapsoriasis group.” 

In actuality, pityriasis lichenoides et varioliformis acuta and 

pityriasis lichenoides chronica are morphologic variations of 

a single inflammatory process, namely, Mucha-Habermann 

disease, and parapsoriasis en plaques and parapsoriasis var-

iegata (large-plaque parapsoriasis) and digitate dermatosis, 

and its smaller, rounder variant, guttate dermatosis (small-

plaque parapsoriasis), are expressions morphologic of a single 

neoplastic process, to wit, mycosis fungoides. In short, both 

small-plaque parapsoriasis and large-plaque parapsoriasis are 

synonyms for flat lesions of mycosis fungoides. Most patients 

with flat lesions of mycosis fungoides never develop elevated 

lesions of the disease (plaques, nodules, tumors), no matter 

the duration of it. That fact does not deny the authenticity 

of a diagnosis of mycosis fungoides for flat lesions of it, 

anymore than it would of Kaposi’s sarcoma, melanoma, and 

angiosarcoma, each of which is diagnosable when lesions 

of them are flat. In sum, the descriptive term parapsoriasis 

should not be used unmodified because it is imprecise, confus-

ing, and potentially harmful to patients; clinicians may be led 



4 Review  |  Dermatol Pract Concept 2015;5(2):1

of a flower, as may be observed in some examples of tricho-

blastoma and trichoblastic (basal cell) carcinoma.

PETECHIA: a pinpoint punctum of extravasated red blood 
cells in the upper part of the dermis.

PHLEGMON: cellulitis brought into being usually by micro-
aerophilic streptococci. The process tends to extend through-

out the dermis and subcutaneous fat to skeletal muscle and 

other soft tissues. Histopathologically, it is seen to consist of 

a sparse, but diffuse, infiltrate of neutrophils, mostly. Phleg-

monous inflammation differs from suppurative inflamma-

tion, which also consists mostly of neutrophils, by displaying 

sparse polymorphs in diffuse distribution, as in erysipelas, 

rather than a dense discrete collection of them.

PIGMENT “INCONTINENCE”: the loss of pigment from 
the epidermis due to damage of epidermal melanocytes and 

basal keratocytes and its ingestion by macrophages within 

the dermis. In some conditions, however, pigment transfer 

to dermal macrophages may be due to phagocytosis of the 

terminal portions of dendritic processes of melanocytes that 

have protruded through the basal lamina.

PIGMENTATION: coloration caused by a variety of pig-
ments. Melanin is responsible for a great range of colors 

in skin, such as black (abundant melanin at all levels of the 

epidermis, including the cornified layer, as in some simple 

lentigines), blue (melanin within melanocytes and melano-

phages in the mid and deep parts of the dermis in many blue 

nevi), tan (sparse melanin in the epidermis of cafe au lait 

spots), gray (diffuse dermal melanosis associated with some 

metastases of melanoma), and ashy melanin increased within 

the epidermis and present in macrophages within the upper 

part of the dermis as in a clinical expression of post inflamma-

tory hyperpigmentation known as erythema dyschromicum 

perstans. Of course, erythema dyschromicum perstans (ashy 

dermatosis) is not an authentic disease just one manifesta-

tion of post-inflammatory pigment alteration. Differences in 

coloration among peoples also are due to melanin. Loss of 

epidermal melanin can be seen in diseases as diverse as vit-

iligo and post-inflammatory hypopigmentation. Skin colors 

in tattoos result from pigments other than melanin, such as 

silver (slate gray), carotene (yellowish orange), cobalt (blue), 

cadmium (yellow), mercury (red), carbon (black or blue), and 

chromium (green). The brown color of hemochromatosis is a 

consequence mostly of melanin in keratinocytes rather than 

of sparse hemosiderin deposited in macrophages.

PILAR: like tricho-, pertains to hair, (the former Latin and the 
latter Greek), in contrast to follicular, which refers specifically 

to an entire follicle including a hair. The two terms pilar and 

tricho-, on the one hand, and follicular, on the other, often 

are used interchangeably and, therefore, incorrectly (i.e., pilar 

patterns of disease, clinically and histopathologically, and that 

each of those patterns can be brought into being by different 

causes, sometimes many of them, as in the case of erythema 

multiforme, in which causes are disparate as infection by 

herpes virus and a drug given systemically. And what has 

just been stated in regard to erythema multiform, erythema 

nodosum, and leukocytoclastic vasculitis obtains equally for 

urticaria, Sweet’s syndrome, and pyoderma gangrenosum. 

On reflection further, the very same concept is applicable to 

psoriasis, lichen planus, and granuloma annulare as well as 

to all other apparently noninfectious inflammatory diseases 

of the skin and subcutaneous fat, from pityriasis rosea to 

nodular vasculitis. And reflection still further makes apparent 

that even so called infectious diseases really are patterns of 

disease! Is suppurative granulomatous dermatitis and pan-

niculitis in conjunction with pseudocarcinomatous prolifera-

tion of keratocytes brought about by any number of different 

“deep fungi” and “atypical mycobacteria” not a pattern? 

And is staphylococcal scalded skin syndrome that stimulates, 

exactly, the appearance of “superficial pemphigus” (foliaceus/ 

erythematosus) not a pattern? And is it not true that except 

for the presence of hyphae, dermatophytosis may mimic all 

of the patterns of psoriasis histopathologic? In sum and in 

short, pattern analysis (in conjunction with an algorithmic 

method) is the surest route to diagnosis of all “inflammatory 

diseases” of the skin and subcutaneous fat, each of which may 

be thought of as a pattern morphologic of disease.

PAUTRIER’S “MICROABSCESS”: a collection of abnormal 
lymphocytes within the epidermis or epithelial structures of 

adnexa of lesions of mycosis fungoides; a misnomer because 

abscess denotes a collection of neutrophils, and Pautrier’s 

collections consist of abnormal lymphocytes.

PEDUNCULATE: a polypoid excrescence that is attached 
to the skin or other flat surface by a stalk, as is the case in a 

fibroepithelial polyp or papilloma.

“PEPPERING” BY LYMPHOCYTES: describes the scatter 
of lymphocytes as solitary units within an aggregation of 

epithelial cells of a proliferation, as occurs in spiradenoma 

and adamantinoid trichoblastoma, or within the epidermis 

as happens often in mycosis fungoides.

PERSISTENCE: in dermatopathology refers to the continua-
tion of a proliferation benign or malignant, at a primary site 

after an attempt, usually surgical and unsuccessful, has been 

made to remove it. Most proliferations described as “recur-

rent” actually are just persistent. Recurrence should only be 

used when referring to true metastasis. (SEE RECURRENCE 

OF MELANOMA)

PETALOID: denotes the appearance histopathologic of 
aggregations of cells in a proliferation that resembles petals 



Review  |  Dermatol Pract Concept 2015;5(2):1 5

i.e., neutrophils, eosinophils, lymphocytes, plasma cells, and 

histiocytes in a section of granuloma faciale.

POLYGONAL CELL: having the shape of a polygon that 
structure being a closed plane figure bounded by straight 

lines usually there are at least three sides and typically five 

or more. When a cell with such a shape is non-epithelial, it 

is likely to be an abnormal melanocyte (of “classic” Spitz’s 

nevus or melanoma), and when epithelial, it is likely to be an 

abnormal myoepithelial cell (as in mixed tumor of apocrine 

type, that neoplasm benign really being infundibulo-apocrine-

sebaceous- follicular). Polygonal cells are often met in com-

pany with plasmacytoid cells.

POLYMORPHIC ERUPTION: more than, one type of skin 
lesion occurring concurrently in an individual, i.e., a combi-

nation of macules, papules, vesicles, and so on, as occurs in 

Mucha-Habermann disease.

POLYMORPHOUS: in reference to infiltrates in lesions, 
composed of several types of cells, as are the mixed-cell infil-

trates of granuloma faciale/erythema elevatum diutinum and 

of histiocytosis X.

POLYPOID: resembling a polyp, an excrescence above the 
skin surface having a narrow base and a stalk, such as an 

acrochordon (i.e., fibroepithelial polyp) or as in an apocrine 

fibroadenoma.

POP OUT: is a colorful description of the way some benign 
proliferations and cysts shoot from the skin after an incision 

made above is carried very near to them. The reason for ease 

of separation from surrounding tissue is that benign prolif-

erations and cysts tend to compress adjacent fibrous tissue 

and, in the process, create a narrow space between them and 

adjacent nearly normal skin. The space, combined with the 

tract of the incision, becomes the route that a neoplasm or 

cyst takes as it flies from its haven. When a surgeon cradles 

some benign neoplasms and cysts in order to encourage them 

to “shell out,” the same space acts as the corridor for their 

release from the skin.

POROID CELL: is one with a round nucleus and scant cyto-
plasm situated lateral to a cuticular cell in a duct of a normal 

apocrine or eccrine gland, it usually being the component 

dominant (the other less conspicuous being a cuticular cell) 

in poromas and porocarcinomas, both ones apocrine and 

eccrine.

PRECANCER (PREMALIGNANCY): The term precancer-
ous implies a benign stage in development of an authentic 

cancer. Skin lesions purported to be “precancerous” are solar 

keratosis, arsenical keratosis, radiation keratosis, Bowen’s 

disease (and its analogue on genitalia, erythroplasia of Quey-

rat), lentigo maligna, and extramammary Paget’s disease. 

sheath acanthoma, trichoblastoma, and pilomatricoma). Each 

of those proliferations consists of cells non-viable like those 

in a follicle, not simply of cells non-viable like those of hair. 

Furthermore, there are no true pilar cysts (although hair 

shafts often are found in steatocystomas, eruptive vellus hair 

cysts, and some infundibular cysts), only ones epidermal (i.e., 

infundibular) and follicular (isthmic-catagen types).

“PINCHING-OFF” SECRETION: describes picturesquely 
the appearance of the distal secretory portion of luminal 

cells that line apocrine glands. The terms “apocrine” secre-

tion, “decapitation” secretion, “pinching off’ secretion, and 

“snouts” are synonyms.

PLAQUE: an elevated, broad, i.e., more than 1.0 cm in 
diameter, lesion. A plaque of psoriasis may come into being 

from extension centrifugally of a single papule or it may be 

a consequence of confluence of many papules. Plaques usu-

ally are acquired, as is the case in lichen simplex chronicus, 

hypertrophic lichen planus, and lichen amyloidosis, but some 

of them are congenital, as in a garment type of congenital 

melanocytic nevus, an epidermal nevus like that known 

as ichthyosis hystrix, and a connective tissue nevus like a 

shagreen “patch.”

PLASMA: is the fluid portion of circulating blood. It is 
distinguished from serum, which is the fluid obtained after 

coagulation.

PLASMOCYTOID: refers to a cell that exhibits cytologic 
features similar to those of a plasma cell, i.e., an eccentri-

cally placed nucleus associated with abundant amphophilic 

cytoplasm. Plasmocytoid cells are found often in some pro-

liferations with apocrine differentiation such as apocrine 

hidradenoma and apocrine mixed tumor, (not uncommonly 

in conjunction with polygonal cells). These cells are also seen 

in benign proliferations, such as “classic” Spitz’s nevus and 

in malignant proliferations, such as melanoma and malignant 

apocrine mixed tumor.

PLATITUDE: (SEE CLICHÉ)

PLEOMORPHISM: denotes variation in size and shape of 
cells, and particularly nuclei of them, in an infiltrate of a 

process proliferative. Pleomorphism is the determinant most 

important of nuclear atypia, the other characteristics conven-

tional of them being large size of nuclei and degree of staining 

inconsistent markedly of them. No direct correlations exist, 

however, between pleomorphism of nuclei and behavior bio-

logic of a proliferation. Nuclei may be strikingly pleomorphic 

in proliferations benign, such as in some “classic” Spitz’s nevi, 

and even in some conditions inflammatory, such as “monster 

cells” in an expression distinctive of dermatofibromas. Pleo-

morphism is not the same as polymorphism, which refers to 

different types of cells present together in a single infiltrate, 



6 Review  |  Dermatol Pract Concept 2015;5(2):1

are present above the dermoepidermal junction, and nuclei of 

melanocytes that may be pleomorphic; that constellation of 

histopathologic findings signifies melanoma in-situ. Biologi-

cally, some examples of so-called lentigo maligna, once having 

extended into the reticular dermis, eventuate in metastases of 

melanoma. In brief, lentigo maligna is not a “precanceroses,” 

but a melanoma that is confined to the epidermis and epithe-

lial structures of adnexa.

Extramammary Paget’s disease is not “precancerous,” but 

an apocrine carcinoma that begins within the epidermis 

and extends far down epithelial structures of adnexa (in the 

same manner as does melanoma). Although many lesions of 

extramammary Paget’s disease remain patches, i.e., in-situ, for 

the lifetime of the patient, some do not; neoplastic cells may 

descend into the dermis and from there metastasize.

In conclusion, a clinician cannot determine by gross exami-

nation alone which solar keratosis will eventually become 

a metastasizing squamous cell carcinoma, which “lentigo 

maligna” will become a metastasizing melanoma, or which 

extramammary Paget’s disease will metastasize as apocrine 

carcinoma. Each of these conditions is cancer, and each must 

be removed completely. No clinician or histopathologist can 

predict which lesion of solar keratosis, arsenical keratosis, 

radiation keratosis, Bowen’s disease, melanoma in-situ, or 

extramammary Paget’s disease, left untreated, will cause 

death as a consequence of metastasis. Clinicians should be 

educated further to appreciate the fact that radical surgery is 

not appropriate for any of these cancers; all that is required 

is total removal nothing more.

By sanitizing cancers with such terms as solar keratosis, len-

tigo maligna, and extramammary Paget’s disease, clinicians 

and pathologists sustain a belief in the erroneous concept of 

“precanceroses.” In actuality, solar keratosis is a squamous 

cell carcinoma, lentigo maligna is a melanoma, and extrama-

mmary Paget’s disease is an apocrine carcinoma.

In addition, there is neither need nor place for the word 

parapsoriasis in the language of dermatology and dermato-

pathology. The diseases now referred to as parapsoriasis can 

be diagnosed accurately as either Mucha-Habermann disease 

or mycosis fungoides. No disease termed parapsoriasis trans-

forms into mycosis fungoides; it is either mycosis fungoides 

or it is Mucha-Habermann disease. This is a considerable 

advance beyond thinking of Brocq, who spawned the concept 

of parapsoriasis and who wrote these lines about it in 1903: 

“It is then quite evident that the group of parapsoriasis, such 

as I define it, established bonds of union between psoriasis 

and seborrhea psoriasiform on one side, and between lichen 

planus and the mild form of pityriasis rubra and mycosis 

fungoides on the other.”

Leukoplakia is a generic term that traditionally has been 

used for precancerous of keratocytes on mucous membranes 

or mucocutaneous junctions. Are the conditions just enumer-

ated precancerous, or are they cancers? All are malignant 

neoplasms.

Histopathologically and biologically, solar keratoses, arseni-

cal keratoses, radiation keratoses, and Bowen’s disease are 

squamous cell carcinomas. Histopathologically, all fulfill 

criteria for squamous cell carcinoma, namely, keratinocytes 

that display crowded nuclei, pleomorphic nuclei, nuclei in 

mitosis, and premature cornification in the form of dyskera-

totic cells. Biologically, each of those lesions may eventuate in 

metastases, a phenomenon that qualifies them as malignant. It 

is curious that dermatologists and pathologists the world over 

diagnose superficial basal cell carcinoma without hesitation 

but they name superficial squamous cell carcinomas by eva-

sions such as “solar keratoses,” “arsenical keratoses,” “radia-

tion keratoses,” and “Bowen’s disease.” If superficial basal cell 

carcinoma is considered to be cancer and not precancerous 

then so should solar keratoses, arsenical keratoses, radiation 

keratoses, and Bowen’s disease be regarded as cancers. They 

are all, types of squamous cell carcinoma.

Histopathologically, solar keratoses sometimes are associ-

ated with suprabasal clefts above which reside acantholytic 

dyskeratotic cells. When that type of solar keratosis becomes 

thicker, histopathologists term the lesion pseudoglandular 

squamous cell carcinoma. No distinct histopathologic bound-

ary exists, however, between any variant of solar keratosis 

and squamous cell carcinoma. It is not surprising, therefore, 

that in no textbook of dermatology, dermatopathology, or 

general pathology can a statement be found where solar kera-

tosis ends and squamous cell carcinoma begins. The reason 

is that solar keratosis is a squamous cell carcinoma, albeit an 

“embryologic one.” The decision about whether a particular 

neoplasm is a solar keratosis or a squamous cell carcinoma 

is the mere whim and fancy of histopathologists. Because the 

judgment is entirely arbitrary, it is wholly without repeatabil-

ity. What has just been written about solar keratosis applies 

equally to arsenic keratosis, radiation keratosis, Bowen’s dis-

ease and bowenoid papulosis—-squamous cell carcinomas all.

Clinically, histopathologically, and biologically, lentigo 

maligna is melanoma. Clinically, the lesion, irrespective of 

size, is asymmetrical with notched borders and variegated 

color, usually shades of brown. Histopathologically, the neo-

plasm fulfills all of the criteria for melanoma in-situ, e.g. an 

increased number of melanocytes disposed as solitary units 

(and later in nests) within the epidermis (and epithelial struc-

tures of adnexa), solitary melanocytes that are not equidistant 

from one another (and neither are the nests), nests that usu-

ally have become confluent in foci, some melanocytes that 



Review  |  Dermatol Pract Concept 2015;5(2):1 7

bizarre-shaped, thin-walled vessel in a patch or plaque of 

Kaposi’s sarcoma.

PSEUDOACANTHOLYSIS: the process whereby non-epithe-
lial cells, melanocytes in particular of some examples of “clas-

sic” Spitz’s nevi and of some melanomas, are separated from 

one another in a manner reminiscent to that of acantholysis 

in which epithelial cells are detached from one another.

PSEUDOCAPSULE: refers to simulation of a capsule, i.e., a 
structure that envelops a proliferation. In general pathology, 

disagreement considerable exists concerning the terms “cap-

sule” and “pseudocapsule.” Some histopathologists consider 

a capsule to be a membrane fibrous formed by stroma of 

normal tissue at the periphery of a proliferation that usually 

is benign. Other histopathologists regard a proliferation as 

encapsulated when the layer of fibrous tissue that surrounds it 

is intrinsic to the proliferation itself. Those latter pathologists 

contend that there are few truly encapsulated proliferations 

and they cite as examples of those few, schwannomas, thymo-

mas, and thyroid adenomas. For them, the layer of fibrous tis-

sue that surrounds most other proliferations may be ascribed 

to fibrous stroma of normal tissue and, therefore, qualifying 

as pseudocapsule. Neither a “capsule” nor a “pseudocapsule” 

is requisite for any diagnosis with specificity in dermatohis-

topathology. The alterations fibrous in point nearly always 

are caused by compression of surrounding normal tissue by a 

benign proliferation or cyst. Clefts tend to form between com-

pressed fibrous tissue that surrounds a benign proliferation 

and the relatively normal tissue adjacent. As a consequence 

of such clefts encircling, a benign proliferation tends to “pop 

out” when incision is made sufficiently deep above it. The 

attributes just described are not seen as a rule in malignant 

proliferations. In sum, so-called capsule and pseudocapsule 

are merely compressed connective tissue.

PSEUDOCARCINOMATOUS HYPERPLASIA: is a prolif-
eration of epithelial cells that, by silhouette, simulates a car-

cinoma, usually a squamous-cell carcinoma, but by cytologic 

features does not. The “Pseudocarcinomatous” appearance 

results from marked hyperplasia of epithelial structures of 

adnexa, i.e., infundibular epidermis and eccrine ducts. Those 

adnexal epithelial structures normally extend far into the 

dermis, and it is for that reason hyperplasia of them may 

result in simulation of an epithelial malignant neoplasm, i.e., 

a carcinoma. Although some keratocytes in the pseudocarci-

nomatous hyperplastic epithelium may be in mitosis, nuclei 

are not strikingly crowded or pleomorphic, in contrast to the 

usual situation in many squamous-cell carcinomas.

Pseudocarcinomatous hyperplasia may be secondary to 
another pathologic process at that site, i.e., granular neoplas-
tic cells in granular-cell schwannoma, infectious agents such 
as atypical mycobacteria in swimming-pool granuloma and 

PROLIFERATION: an increase in number, usually of cells. 
A proliferation of epithelial cells in skin may be divided into 

those that are epidermal and those that are adnexal. A prolif-

eration of epidermal keratocytes may be psoriasiform evenly, 

i.e., elongated rete ridges of about equal length, those alter-

nating with dermal papillae of about equal length, as in pso-

riasis at its apogee, psoriasiform unevenly i.e., elongated rete 

ridges that are not of uniform length but that alternate none-

theless with dermal papillae to create an undulate pattern, as 

in longstanding nummular dermatitis, jagged, i.e., serrations 

at the base of a thickened epidermis, as in lichen planus, and 

mammillated, papillated, or digitated, i.e., the surface of the 

epidermis resembling breasts, nipples, or fingers, respectively, 

as in some examples of nevus sebaceous, acanthosis nigricans, 

and verruca vulgaris, respectively. “Verrucous” is a synonym 

for “digitate.” Proliferation of cells of epithelial structures of 

adnexa, i.e., the upper part of eccrine ducts and of infundibu-

lar epidermis, may be slight or marked the latter sometimes 

simulating squamous cell carcinoma (pseudocarcinomatous), 

as seen in some examples of halogenodermas, infections by 

deep fungi and atypical mycobacteria, and the verrucous 

stage of incontinentia pigmenti. Proliferation of melanocytes 

may be categorized according to an increase in the absolute 

number of normal appearing melanocytes per unit area of 

dermoepidermal junction or basal layer of epidermis, either 

as solitary units entirely or associated with nests.

Proliferation also may be a term generic for any increase 

in the number of cells other than ones inflammatory and, 

therefore, applicable to what are designated conventionally 

neoplasms (both benign and malignant), hyperplasias, hamar-

tomas, malformations, structures ectopic, etc. No agreement 

has been reached after more than 150 years about definition 

of the above. Moreover, and more important, these definitions 

are not essential to diagnosis with specificity. Once the diag-

nosis with specificity has been accomplished by naming things 

for what they are such as in the case of verruca vulgaris with 

sebaceous differentiation, fibrofolliculoma/ trichodiscoma, 

nevus comedonicus, spiradenoma, and microcystic adnexal 

carcinoma, a knowledgeable clinician should understand 

immediately the implications biologic of the specific diagnosis 

just stated in regard to management of the patient.

PROLIFERATION OF ATYPICAL MELANOCYTES: an 
increase in number of melanocytes whose nuclei are atypical 

those cells being present in, and sometimes above, the basal 

layer of the epidermis and of epithelial structures of adnexa. 

The phrase is descriptive and does not convey a diagnosis 

with specificity; such a proliferation may occur in melanoma 

in situ, as well as in a junctional “classic” Spitz’s nevus.

PROMONTORY SIGN: describes a projection of a normal 
venule into a larger space created by a newly formed, often 



8 Review  |  Dermatol Pract Concept 2015;5(2):1

dense, diffuse infiltrates of histiocytes, some nuclei of which 

are pleomorphic and in mitosis, may resemble a poorly differ-

entiated squamous cell carcinoma. What some authors con-

sider to be “pseudocancerous,” i.e., florid oral papillomatosis, 

epithelioma cuniculatum, and giant condyloma, are really 

authentic verrucous carcinomas. “Solitary” keratoacanthoma 

cannot be a pseudomalignancy because it sometimes metasta-

sizes as the squamous cell carcinoma that it is.

Pseudocarcinomatous hyperplasia refers specifically to 

silhouettes that may simulate those of either a basal cell 

carcinoma or a squamous cell carcinoma. A simulator of 

superficial basal cell carcinoma is follicular germ induced by 

fibrohistiocytic elements of dermatofibroma, and a mimic of 

squamous cell carcinoma is the adnexal epithelial hyperplasia 

often associated with infections by deep fungi and atypical 

mycobacteria. A distinction must be made between the terms 

pseudocarcinoma, on one hand, and pseudocarcinomatous 

hyperplasia on the other. The former is a clumsy attempt to 

render a specific diagnosis, whereas the latter is a description 

of adnexal epithelial hyperplasia the outline of which resem-

bles a carcinoma. The term pseudocarcinomatous hyperplasia 

is not meant to be a specific diagnosis. Pseudocarcinomatous 

hyperplasia usually consists of a proliferation of infundibular 

and/or eccrine ductal epithelium that assumes the outline of 

a squamous cell carcinoma, but nuclei of spinous cells are 

neither crowded nor atypical.

The same principle that obtains for pseudomalignancy in gen-

eral applies equally to pseudolymphomas of the B-cell type 

in which the architectural pattern resembles roughly that of 

a lymphoma of the B-cell type, namely, nodular aggregations 

composed mostly of lymphocytes distributed throughout 

the dermis and sometimes in the subcutaneous fat, but the 

lymphocytes are small and devoid of prominent nuclear pleo-

morphism. It has become increasingly apparent that many 

lesions on faces diagnosed as pseudolymphomas have proved 

to be authentic lymphomas. Lymphomatoid papulosis often 

is listed among the pseudolymphomas, but, in reality, it is a 

Ki-1 lymphoma. Actinic reticuloid, a persistent light reaction, 

does not mimic a lymphoma histopathologically, and neither 

does pityriasis lichenoides (Mucha-Habermann disease). The 

lymphocytes in actinic reticuloid and Mucha-Habermann 

disease are small and monomorphous.

Pseudosarcomas tend to have the silhouette of a benign neo-

plasm, but nuclei of neoplastic cells display pleomorphism, 

i.e., the mesenchymal cells (“floret cells”) of pleomorphic 

fibromas and pleomorphic lipomas.

There are several “pseudomelanomas,” only one of which is 

accompanied, and only episodically, with striking pleomor-

phism of nuclei, namely, “classic” Spitz’s nevus. That nevus, 

however, like all nevi, has the architectural pattern of a benign 

deep fungi in chromo mycosis, halogens in bromoderma, and 
persistent rubbing of the skin in prurigo nodularis.

PSEUDOGLANDULAR: resembling (however vaguely) an 
authentic gland, as does the structure that may form in a 

solar keratotic type of squamous-cell carcinoma and is char-

acterized by suprabasal clefts above, which are acantholytic, 

dyskeratotic cells. At its outset, a very superficial squamous-

cell carcinoma of this type is called a solar (actinic) keratosis.

PSEUDOMALIGNANCY: malignancy is fundamentally 
a concept predicated on biologic behavior. A malignant 

neoplasm has the capability to kill either by destruction of 

tissue locally or by metastasis. The irrepressible behavior of 

malignant neoplasms is reflected in certain morphologic cor-

relates, grossly (clinically) and histopathologically. Viewed 

through a microscope, those morphologic attributes usu-

ally are expressed as a particular silhouette and as certain 

cytologic features. As a rule, malignant neoplasms tend to 

be asymmetrical and poorly circumscribed, and to be com-

posed of neoplastic cells disposed in aggregations that vary 

markedly in size and shape, that may have jagged outlines, 

and that tend to become confluent to form sheets of cells. 

Nuclei of cells that constitute malignant neoplasms often are 

pleomorphic, and some are in mitosis. Some mitotic figures 

may be abnormal.

The concept of pseudomalignancy is based on disparity 

between histopathologic appearance and biologic behavior 

of a condition. A pseudomalignancy has either the silhouette 

or the cytologic features usually associated with a malignant 

neoplasm, yet its behavior is uniformly and wholly benign. 

Pseudomalignancies usually are benign neoplasms, but, rarely, 

they may be inflammatory diseases, such as dermatofibromas 

with “monster cells.” Irrespective of the essential pathologic 

process, the term pseudomalignancy (pseudocarcinoma, 

pseudolymphoma, pseudosarcoma, and pseudomelanoma) 

is vague and descriptive of a benign condition; it is not a 

specific diagnosis framed in the language of clinical derma-

tology, i.e., trichoblastoma, response to the bite of a tick and 

“classic” Spitz’s nevus. Pseudomalignancies neither precede 

nor transform into authentic malignancies. The word should 

rarely be used.

Furthermore, pseudocarcinoma may refer to a benign neo-

plasm, a hyperplasia, or an inflammatory process that mimics 

a carcinoma, usually a basal cell carcinoma or a squamous 

cell carcinoma. For example, desmoplastic trichoepithelioma, 

a particular expression of trichoblastoma typified by columns 

of follicular germinative cells, often mimics a morpheaform 

basal cell carcinoma histopathologically; the hyperplasia 

of surface epithelium above a granular cell neoplasm may 

simulate squamous cell carcinoma, and a very early lesion of 

xanthogranuloma, an inflammatory process that consists of 



Review  |  Dermatol Pract Concept 2015;5(2):1 9

and/or the subcutaneous fat. Purpura can be classified as 

subsequent to inflammatory disease, as in Schamberg’s dis-

ease, leukocytoclastic vasculitis, and Mucha-Habermann 

disease, and as unaffiliated with an inflammatory disease, as 

is the case for solar purpura, thrombomcytopenia, and dis-

seminated intravascular coagulopathy.

PUSHING MARGINS: an image used to convey the smooth, 
round borders of a well-circumscribed (usually benign) 

neoplasm that appears to grow centrifugally. This term is 

to be eschewed. It is a cliché since it cannot be seen under a 

microscope. (i.e., pushing).

PUSTULE: clinically, an elevated, circumscribed collection 
of pus (neutrophils and necrotic debris of neutrophils) and, 

histopathologically, a collection of neutrophils within an epi-

dermis (surface and/or infundibular) and, much less often, an 

eccrine unit. A variety of names, some eponymic, have been 

given to types of pustules situated within cutaneous epithelia. 

Discrete pustules in the mid-spinous zone of psoriasis are 

termed “Munro’s micrabscesses”; sponge-like pustules in the 

upper reaches of the epidermis, particularly of psoriasis and 

variants of it, ranging from acrodermatitis continua (Hal-

lopeau) through keratoderma blenorrhagicum to subcorneal 

pustular dermatitis (Sneddon and Wilkinson), are known as 

spongiform pustules of Kogoj; abscesses positioned beneath 

the cornified layer of an epidermis are referred to as subcor-

neal pustules. None of those types of pustules is specific for 

anyone disease. So-called Munro’s micro abscesses also may 

be seen in dermatophytosis, spongiform pustules in halogeno-

dermas, and subcorneal pustules in pyoderma gangrenosum. 

The various appearances of pustules histopathologically 

reflect a moment in time at which a biopsy interrupted 

migration of neutrophils from capillaries in dermal papillae 

to the cornified layer of the epidermis, which is their destina-

tion ultimately. For reasons not understood, neutrophils in 

eruptive (guttate) psoriasis hone to the summit of mounds 

of parakeratosis.

Most pustules in skin are infundibular epidermal rather than 

surface epidermal, and most of them are idiopathic. Many 

of the remainder are infectious, i.e., bacterial (staphylo-

cocci), fungal (dermatophytes), viral (herpes), and spirochetal 

(Treponema palladium). Sometimes, what looks like a pustule 

in infundibular epidermis is seen by conventional microscopy 

to consist of countless eosinophils and many fewer neutro-

phils. Examples of this phenomenon, termed badly “eosino-

philic folliculitis” (the condition, actually, is an infundibulitis, 

not a folliculitis, and it is not eosinophilic, but rather is domi-

nated by eosinophils), are encountered in Ofuji’s disease and 

in some patients with HIV. The term pustule is reserved for 

any nonsolid lesion that clinically is filled with “pus” and pus-

tule histopathologically only for collections of neutrophils in 

neoplasm, to wit, it is symmetrical and sharply circumscribed. 

Some “classic” Spitz’s nevi have several architectural features 

in common with melanoma, such as a scatter of melanocytes 

at all levels of the epidermis, a phenomenon that is also 

encountered in the other distinctive melanocytic nevi such 

as congenital nevi biopsied shortly after birth; some junc-

tional and compound nevi situated on the palms and soles; 

junctional and compound nevi situated on particular ana-

tomic sites such as the nipple and areola, genitalia, perianal 

region, intertriginous regions, and umbilicus; and junctional 

and compound nevi that persists after inadequate surgical 

removal.

In sum, whenever possible the diagnoses should be made 

for what they are. The term “pseudo” anything has limited 

usefulness.

PSORIASIFORM: resembling a fully developed lesion of 
psoriasis clinically, i.e., a reddish plaque covered by scales, 

and/or histopathologically, i.e., elongated rete ridges of about 

equal length that alternate with long dermal papillae to form 

a strikingly undulate pattern. The concept of psoriasiform 

just stated is parochial, however, because it applies only to 

lesions formed fully of that remarkably protean disease. 

Clinical expressions of psoriasis range from smooth-surfaced 

guttate papules devoid of scale to exfoliative erythroderma, 

from discrete pustules on palms and soles to widespread 

pustules accompanied by signs and symptoms of systemic 

character, and from plaques with slight scale to “extremely 

thick side.” Each of these manifestations of psoriasis has an 

analogue histopathologically. In theory, therefore, simulation 

of any of the manifold expressions of psoriasis, clinically and 

histopathologically, is psoriasiform.

PUNCH BIOPSY: refers to a procedure used to obtain a cylin-
drical portion of skin that consists of epidermis and dermis, 

and even of subcutaneous tissue. The procedure is performed 

with an instrument known as a punch, the diameter of which 

may range from 2 to 8 mm and whose cutting edge is usu-

ally made of steel but sometimes of plastic. A sample of skin 

is taken by introducing the round blade of the punch into 

the skin, to which it is oriented perpendicularly, and, under 

pressure, rotating the instrument, back and forth, until it has 

penetrated the entire dermis and entered the subcutaneous 

fat. The procedure is simple and rapid and leaves a wound 

that is easy to close with a suture or that may heal with sec-

ond intention and with little scar. Of course, there are many 

indication and contraindications for the use of this procedure. 

(SEE BIOPSY, RAZOR BLADE REMOVALS)

PURPURA: a purple color caused by hemorrhage in the skin. 
Petechiae are pinpoint hemorrhagic macules and ecchymoses 

are hemorrhagic patches. A hematoma is extensive hemor-

rhage in a somewhat discrete locus in the reticular dermis 



10 Review  |  Dermatol Pract Concept 2015;5(2):1

RAZOR BLADE REMOVALS: in this technique a razor blade 
which bends (it is usually the equivalent of a “Gillette blue 

blade” cut in half or whole) is used to perform shave horizon-

tal or tangential removals. The blade may also be bowed into 

different shapes to perform saucerization removal/excisions 

by a dermatologist who is experienced with it. Some find this 

far superior to a “knife blade” to perform saucerization. Some 

refer to saucerization as “scoop removals.” (SEE BIOPSY, 

SHAVE REMOVALS, SEE SAUCERATIZATION)

RECURRENCE OF MELANOMA: the following applies to 
all other proliferations as well varying of course if the prolif-

erations are benign or malignant. (i.e., benign proliferations 

can also persist)

The issue of “recurrence of melanoma” is central to the matter 

of extent of margins for excisions of melanoma and to the 

issue of prognosis for a person who bears a melanoma. Vir-

tually every textbook of dermatology and of general surgery 

advocates wider excisions for thicker melanomas based on 

the assertion that the likelihood for recurrence of melanoma 

is enhanced by narrow margins of excision, especially for 

thicker lesions. That declaration is without validity.

Recurrence means to occur again, and in the realm of mela-

noma the phenomenon of recurrence may assume one of 

two forms, namely, persistence of a primary melanoma at the 

original local site, as a consequence of incomplete removal, 

or metastasis. The implications of those very different expres-

sions of “recurrence” are profound, to wit, persistence of 

a primary melanoma may not spell a grave prognosis (i.e., 

re-excision may be curative, especially if the neoplasm is still 

very thin), whereas metastasis, for practical purposes, may 

signal a grave prognosis.

Unfortunately, all too many general pathologists and sur-

geons use the term recurrence indiscriminately, i.e., they 

fail to make a distinction between recurrence of a primary 

neoplasm at the initial local site (persistence) and recurrence 

that presents itself as neoplastic cells at a site some distance 

from the primary one (metastasis). (SEE PERSISTENCE.) The 

literature of pathology and surgery with regard to “margins 

of excision for melanoma” is peppered by the word “recur-

rence,” yet rarely is an attempt made by authors to qualify 

the type of recurrence, i.e., persistence or metastasis. Without 

such clarification, a reader is unable to judge the authenticity 

of the statement that recurrence of a melanoma is more likely 

if margins of the excision are narrow. If by recurrence the 

authors of these papers actually mean metastasis (as they usu-

ally do), then a patient’s prognosis is grim and could not have 

been altered, no matter how wide and deep the margins of 

excision because the metastasis must have occurred before the 

excision of the primary melanoma, assuming that the primary 

neoplasm was removed entirely. Parenthetically, authors of 

an epithelium, usually, the epidermis; we do not use the word 

pustule for aggregations of eosinophils within an epithelium.

PYKNOSIS: one of the specific signs of necrosis marked by 
shrinkage and intense hyperchromasia of nuclei. During cell 

death, some nuclei may shrink as chromatin condenses to a 

solid, densely basophilic mass. That combination of findings 

constitutes pyknosis.

PYRIFORM: means having the form of a pear and, when 
applied to proliferation epithelial, refers usually to lobules 

of epithelial cells that assume the shape of a pear, such as 

normal lobules of a sebaceous gland and abnormal ones of 

nevus sebaceous.

– R –
RACEMIFORM: describes an appearance like a cluster of 
grapes or a bunch of berries formed by epithelial cells in some 

proliferations. In cutaneous pathology, the best example of 

racemiform arrangement of cells is found in trichoblastoma.

RADIAL GROWTH PHASE: a concept introduced by Rich-
ard Reed and co-workers who stated that the “variants of 

malignant melanoma that grow radially at the dermoepi-

dermal interface are expressions of an evolutionary process 

in which melanoma cells proliferate and spread along the 

dermal-epidermal interface or in the immediate subadjacent 

papillary dermis for a variable period of time before they 

acquire the capacity to survive and produce aggregates of 

tumor cells in the dermis (vertical growth phase).” Those 

collaborators have suggested that the vertical growth phase, 

defined by them as the presence of an “expansile nodule” in 

the papillary dermis, may indicate potential for metastasis, 

whereas the radial growth phase is associated with no capa-

bility for metastasis. The terms radial and vertical, however, 

are not contrasting; vertical is a component of radial. Verti-

cal and horizontal are contrasting. Moreover, “radial growth 

phase” and “vertical growth phase” of melanoma simply 

are replacements for the now abandoned concept of Clark’s 

“levels of invasion of melanoma.” Radial growth phase 

superseded Clark’s levels I and II, whereas vertical growth 

phase substituted for levels III, IV, and V. Notions of radial 

growth phase and vertical growth phase of melanoma are not 

relevant either to diagnosis or to management of melanoma. 

In reality, no histopathologist is able to determine truly where 

the so-called radial growth phase ends and the so-called ver-

tical growth phase begins, and no surgeon’s hand should be 

guided by those “phases”; every melanoma, irrespective of 

thickness of it, should be removed with just enough normal 

skin around it to ensure that that goal has been achieved. In 

short, assignment of phases radial and vertical is engagement 

in mysticism and should be eschewed.



Review  |  Dermatol Pract Concept 2015;5(2):1 11

The concepts stated above vary depending on the dermato-

pathologist.

Morphologically, the effects of the battle between lympho-

cytes and melanocytes of melanoma express themselves in 

three fashions: fibrosis, melanosis, and a combination of 

fibrosis and melanosis. These descriptive terms, i.e., fibrosis 

and melanosis, apply to the residual changes of complete and 

focal regression of primary melanoma in a thickened papil-

lary dermis beneath an epidermis whose normal undulations 

have been muted or effaced. Fibrosis refers to fibroplasia, 

usually of delicate fibrillary bundles of collagen, in a thick-

ened papillary dermis. Sometimes the papillary dermis may be 

more than five times its normal thickness and measures more 

than 1.0mm as a consequence of formation of new collagen 

by fibrocytes. Fibrosis often is accompanied by diffuse depos-

its of mucin, sparse lymphocytic infiltrates, variable numbers 

of melanophages, i.e., from practically none to many, and 

telangiectases. In contrast, melanosis denotes a dense band of 

melanophages in a papillary dermis that may be as thickened 

by macrophages as it may be by fibroplasia. The epidermis 

above a zone of melanosis also shows diminution in the 

normal pattern of rete ridges and dermal papillae. In some 

specimens, sections exhibit features of fibrosis and melanosis 

in the same thickened papillary dermis. In those cases, fibrosis 

tends to be present in the upper part of the expanded papil-

lary dermis and melanosis in the lower part. When melanosis 

is noted, a diagnosis of regression of melanoma may be issued 

without equivocation. The findings of melanosis are specific. 

That is not the case for fibrosis in regression of melanoma. 

Changes indistinguishable from it may be found in regres-

sion of lichen planus like keratosis, a solar lentigo-reticulated 

seborrheic keratosis that attracts lichenoid infiltrates of lym-

phocytes to it and is subsequently destroyed by them. Even 

the numerous necrotic keratocytes so often observed in the 

epidermis and papillary dermis of a regression of lichen pla-

nus like keratosis may be noted in some lesions of melanoma 

undergoing regression by fibrosis. Regression of “halo” nevus 

as a result of the effects of lymphocytes on melanocytes also 

takes the form of fibroplasia but never of melanosis. A “halo” 

nevus that has regressed completely can be distinguished, 

usually, at scanning magnification from a melanoma that 

has regressed completely by fibrosis: the two have different 

silhouettes. In most instances, a regressed “halo” nevus has 

the silhouette of a Clark’s nevus, i.e., it is small, symmetrical, 

and slightly domed, whereas a melanoma usually is broader, 

asymmetrical, and flattish.

What is the significance of regression of primary melanoma? 

Complete regression of melanoma, in our experience is syn-

onymous with the existence of metastases from that primary 

melanoma. As we conceive it, prior metastasis to a regional 

lymph node is mandatory for occurrence of complete regres-

papers about this subject often define local recurrence as the 

appearance of a melanoma within 2 to 5 cm of the primary 

site. Those melanomas however represent satellite metastases, 

not persistent primaries.

If, one day, dermatologists, pathologists, and surgeons are 

to communicate lucidly with one another about recurrence 

of melanoma and its implications for margins of excision of 

melanoma and for prognosis, then they must not employ the 

same word recurrence for two entirely different phenomena, 

i.e., persistence and metastasis. Only then can meaningful 

studies be undertaken of the relationship between extent of 

margins of excision for primary melanomas and prognosis of 

those neoplasms. And only then can those studies be assessed 

critically.

RE-EPITHELIALIZATION: refers to a process by which a 
new epidermis is generated from infundibular and eccrine 

ductal epithelia.

REGRESSION: in the realm of cutaneous neoplasia, refers to 
involution of a benign or a malignant proliferation, usually as 

a consequence of the effects of inflammatory cells on prolif-

erations. The commonest benign proliferation that undergoes 

regression is solar lentigo (or its more advanced expression, 

reticulated seborrheic keratosis) to which a dense lichenoid 

infiltrate of lymphocytes is attracted. That lesion, known as 

a lichen planus-like keratosis, eventually disappears, leaving 

in its wake a papillary dermis thickened by fibroplasia, a 

sprinkling of lymphocytes, melanophages, and telangiectasias.

Solitary keratoacanthomas nearly always regresses after 

months as a consequence, in part, of a dense mixed infiltrate 

of inflammatory cells, leaving as residuum a dermal scar. 

Regression of primary melanoma is a phenomenon that 

involves the superficial vascular plexus, a thickened papillary 

dermis, and the epidermis. Requirements for induction of 

regression are: (1) melanocytes of melanoma in the epidermis 

and papillary dermis, and (2) lymphocytic infiltrates around 

the vessels of the superficial plexus, in lichenoid array within 

the “melanomatous” component of the papillary dermis, and 

scattered among neoplastic melanocytes of melanoma within 

the epidermis. In brief, cytotoxic products of lymphocytes kill 

neoplastic cells of melanoma situated in the papillary dermis 

and epidermis. Rarely, all of the cells of the melanoma in 

the epidermis are destroyed by the effects of lymphocytes, a 

condition termed “complete regression” of melanoma. Often, 

all of the melanocytes of melanoma in a discrete focus of the 

papillary dermis and epidermis are obliterated by the action 

of lymphocytes; a circumstance designated “focal regres-

sion” of melanoma. Episodically, melanocytes of melanoma 

are eliminated partially in the papillary dermis and in the 

epidermis or entirely in the papillary dermis and not at all in 

the epidermis, a phenomenon known as “partial regression.” 



12 Review  |  Dermatol Pract Concept 2015;5(2):1

composed of elements like those that constitute basement 

membranes normal in the skin and that is found around 

aggregations of cells in cylindroma and cylindrocarcinoma, 

as well as, at times, in spiradenoma.

RIPPLE PATTERN: for purposes practical the epithelial ele-
ments essential always being immature sebocytes, refers to 

an image histopathologic created by epithelial cells seemingly 

undifferentiated arrayed in lines wavy that gives the impres-

sion of the appearance of rippling of water, it being a sign 

specific of sebaceoma.

ROUND MELANOCYTE: small, round, “lymphocytoid” 
melanocytes are commonly present in the middle or lower 

portions of intradermal melanocytic nevi. They are smaller 

in diameter than the more superficially situated cuboidal or 

epithelioid melanocytes, have centrally placed compact nuclei, 

and usually do not contain melanin. Small round melanocytes 

with atypical nuclei sometimes are found in melanomas. In 

these cases there may be only a few nests of such cells or they 

may constitute the bulk of the neoplasm. Large, seemingly 

round cells are seen in “classic” Spitz’s nevi and some blue 

nevi as the result of section of spindle cells perpendicular to 

their long axes. Large round cells with atypical nuclei are 

commonly found in melanomas.

– S –
SARCOMA: A neoplasm malignant made up of cells non-
epithelial.

S-100 PROTEIN: is an acidic protein composed of a and b 
subunits. It was thought initially to be specific for neuro-

ectodermal cells and tissues. Subsequently, the protein has 

been shown to be ubiquitous in distribution, including tissues 

derived from ectoderm (i.e., astroglial cells, melanocytes, 

neuroblasts, Schwann cells), mesoderm (i.e., Langerhans’ 

cells, adipocytes), and endoderm (i.e., neuroendocrine cells 

of respiratory and gastrointestinal tracts). Many neoplasms 

that differentiate toward those normal cells and tissues also 

react to this protein. S-100 protein is found in secretory cells 

of eccrine glands, but the presence of S-100 protein in a pro-

liferation with adnexal differentiation does not necessarily 

signify eccrine differentiation. S-100 protein also is present in 

some proliferations with indubitable apocrine differentiation, 

evidenced by apocrine secretion, and in many neoplasms in 

the breast, probably because mammary glands and lactiferous 

ducts have capability for apocrine metaplasia.

Despite its lack of total specificity, antibodies directed against 

S100 protein continue to play a central role in establishing 

a diagnosis of melanoma in the skin. The routinely used, 

commercially available polyclonal antibodies are directed 

against both subunits of S100 protein and recognized protein 

sion of primary melanoma. Sensitized lymphocytes return 

from the involved node to the skin where they “hone in” on 

the melanoma and destroy it. Different authors have different 

interpretations concerning the significance of focal regression 

of primary melanoma. Some aver that it is a good prognostic 

sign, whereas others claim that it has no prognostic signifi-

cance. We are not certain of the meaning of focal regression of 

primary melanoma, biologically, but we infer that if complete 

regression signifies a grave prognosis focal regression prob-

ably does not herald a good one.

However of this later point there is no certainty.

Last, there is the subject of regression of metastasis of mela-

noma to skin. That phenomenon is seen rarely, but when it 

is encountered, the setting tends to be a satellite metastasis 

in the same histopathologic section as a primary melanoma. 

When melanophages in discrete collections marked by jag-

ged outlines are discerned in foci within reticular dermis and 

even within the subcutaneous fat, the diagnosis is melanosis 

as a consequence of regression of a metastasis of melanoma.

RETICULAR ALTERATION: (SEE BALLOONING)

RETICULATE: refers to one manifestation of a pattern 
net-like that can be visualized in the skin by both inspection 

gross and examination histopathologic. Examples of pat-

terns reticulated observable clinically are livedo reticularis, 

confluent and reticulated papillomatosis, and parapsoriasis 

reticulata (parakeratosis variegata), which is a manifestation 

of mycosis fungoides. Patterns reticulate seen histopatho-

logically result from interconnection of cells epithelial in 

conditions as diverse as trichoblastoma, mantle adenoma, 

and fibroepitheliomatous trichoblastic (basal cell) carcinoma.

RETIFORM: retiform is a synonym for reticulate.

RIBBONS OF COLLAGEN: describe the appearance of 
strips of collagen that resembles ribbons in proximity close to 

one another as is the situation in fibrofolliculoma/trichodis-

coma, they being aligned perpendicular to struts of mantle 

epithelium that forms a pattern fenestrated at a stage “early” 

in that particular hamartoma (fibrofolliculoma) and being 

distributed haphazardly later in the course of the same ham-

artoma (trichodiscoma).

RICHLY FIBROCYTIC STROMA: in a proliferation of 
epithelial cells adnexal describes connective tissue in which 

fibrocytes are present in large number and in which bundles 

of collagen tend to be delicate and fibrillary, often being 

joined by mucin in quantity, as is the case in small nodular 

trichoblastoma, type racemiform of trichoblastoma, and 

fibroepitheliomatous trichoblastic (basal cell) carcinoma.

RIMS OF BASEMENT MEMBRANE MATERIAL: describes 
a layer homogenous and eosinophilic of uniform thickness 



Review  |  Dermatol Pract Concept 2015;5(2):1 13

parakeratosis of Darier’s disease and of porokeratosis), and 

greasy (i.e., the delicate, laminated, pigmented orthokeratosis 

of seborrheic keratosis).

Scale must be distinguished clinically from keratosis, i.e., a 

horny excrescence, which is not a flake of cornified cells, but 

which may be orthokeratotic in a lesion of isolated epider-

molytic hyperkeratosis, parakeratotic in one of acantholytic 

dyskeratotic acanthoma, and both together in a solar kera-

tosis. Diagnosis histopathologic of many skin diseases can be 

accomplished by study of the epidermal cornified layer alone, 

using only low magnification of a conventional microscope. 

For example, mounds of parakeratosis that house neutrophils 

at their summit signify eruptive psoriasis or dermatophytosis, 

mounds of scale-crusts at lips of infundibular ostia indicate 

seborrheic dermatitis, alternation of short rectangular or 

square zones of orthokeratosis and parakeratosis in both 

horizontal and vertical directions telegraphs pityriasis rubra 

pilaris, marked compact orthokeratosis on hair bearing skin 

denotes lichen simplex chronicus, and a slice of orthokera-

tosis above a slice of parakeratosis, i.e., the “sandwich sign,” 

should call to mind dermatophytosis in which hyphae repose 

in orthokeratotic cells very near the middle of the sandwich. 

Corneocytes in excessive number may cause infundibula to 

widen, as in keratosis pilaris and discoid lupus erythematosus, 

and even to become sac-like, as in an infundibular cyst.

SCALE-CRUST: a combination of scale (cornified cells, usu-
ally parakeratotic ones) and crust (serum that contains blood 

cells, either, red, white, or both). Scale-crusts cover spongiotic 

psoriasiform dermatitides, allergic contact dermatitis, and 

nummular dermatitis in particular, but they are found also at 

the lips of ostia of infundibula in seborrheic dermatitis. Scale 

usually results from acceleration in epidermopoiesis that is 

associated with an increase in the number of spinous cells. 

Crust usually is a consequence of spongiosis or of erosion 

secondary to excoriation, following which serum flows to 

the surface of the skin.

SCANNING: in histopathology pertains to observing an 
entire section quickly, from one end to another, using an 

objective with the lowest magnification, i.e., between X 1.0 

and X 2.5 objective of a conventional microscope. Scanning 

magnification is crucial to accurate diagnosis in dermato-

pathology because it permits analysis of patterns formed by 

cells, i.e., infiltrates of inflammatory cells around vascular 

plexuses, in the interstitium, and within epithelial struc-

tures, and infiltrates of neoplastic cells as they have become 

arranged in distinctive silhouettes. Architectural features 

visualized with scanning magnification are requisite if an 

algorithmic method based on pattern analysis for specific 

diagnoses of skin diseases is to be used effectively for inflam-

matory diseases and for proliferations of various kinds with 

expressed in melanocytes, Langerhans cells, neutrophils, and 

nerves within the skin. In some settings, macrophages may 

also be detected with anti S100 protein antibodies. It is impor-

tant to note that virtually all melanocytes, whether occurring 

singly in the epidermis, as benign nevus nests, or as melanoma 

cells, express S100 protein within their cytoplasms. Reported 

sensitivity rates have been reported for less common subtypes 

including mucosal, sinonasal and desmoplastic melanomas. 

Metastatic melanoma is also almost always detected with 

antiS100 protein antibodies. Melanomas may fail to express 

S100 protein, though this is exceedingly uncommon.

When attempting to identify a subpopulation of cells within 

the epidermis, it is important to evaluate the immunostaining 

in concert with the routine histology in order to separate Lang-

erhans cells from melanocytes. (The addition of anti-CD1a 

antibody would further help in this distinction, as Langer-

hans cells invariably express this antigen, while melanocytes 

do not). More commonly, dermatopathologists are asked to 

identify a population of poorly differentiated spindle-shaped 

cells within the dermis. In this setting, anti-S100 protein anti-

bodies can be an invaluable aid. Virtually all desmoplastic 

melanomas express this protein, and virtually none of the 

other neoplasms in this histologic differential diagnosis do 

so. Thus, results from this test are very helpful in narrowing 

a differential diagnosis, and when used in conjunction with 

other antibodies, can help establish a diagnosis in most cases.

SATELLITE LESION: (SEE METASTASIS OF 
 MELANOMA)

SATELLITOSIS: a metastasis within 5 centimeters of the 
primary neoplasm, which sometimes is apparent in the same 

tissue section; an evidence of distant metastases. The terms 

satellite, in-transit, regional and distant applied to metastasis 

are artificial and misleading and not necessary.

SAUCERIZATION: a variant of shave removal using a razor 
blade, which is bowed for deeper removals. (SEE RAZOR 

BLADE REMOVAL)

SCALE: a collection of cornified cells seen clinically as a dry, 
thin flake which may assume various sizes, shapes, and colors. 

Scale may consist of orthokeratotic cells, parakeratotic cells, 

or both of them jointly, it being lodged usually atop surface 

epidermis but sometimes being contained within the invagi-

nation formed by infundibular epidermis. Scale is described 

as micaceous (i.e., the confluent parakeratosis of psoriatic 

plaques), branny (i.e., the focal scale-crust of seborrheic der-

matitis), powdery (i.e., the orthokeratosis of tinea versicolor 

in which the normal basket-weave pattern of the thickened 

cornified layer is preserved), adherent (i.e., the confluent 

compact and laminated orthokeratosis of ichthyosis vul-

garis and X-linked ichthyosis), coarse (i.e., the focal vertical 



14 Review  |  Dermatol Pract Concept 2015;5(2):1

a puny inferior segment, and one or more large sebaceous 

glands.

SEBACEOUS SECRETION: is holocrine secretion of over-

mature sebaceous cells. It represents the end product of 

maturation of sebocytes.

SEBOCYTE: is a synonym for sebaceous cell, a cell derived 

in embryonic life from a follicular germ. Immature sebocytes 

have round nuclei and scant, slightly vacuolated cytoplasm; 

mature sebocytes have scalloped nuclei and markedly vacu-

olated cytoplasm. Sebocytes in an embryo originate in the 

middle bulge at the junction of the infundibulum and isthmus. 

Sebocytes are aggregated in lobules that, in conglomerate, 

form a gland; a duct collects sebaceous (holocrine) secretion 

and transports it to an infundibular epidermis, from whence 

it is carried, as sebum, through an ostium to the surface of 

the skin.

SEBORRHEIC: purportedly relating to sebaceous glands or 

sebum. In actuality, however, conditions such as seborrheic 

dermatitis and seborrheic keratosis bear no direct relation-

ship to sebaceous glands or to sebum. Seborrheic distribution 

of lesions refers to sites like those involved by seborrheic 

dermatitis, to wit, the forehead, malar region, paranasal and 

nasolabial folds, retroauricular region, and sternal region.

SEBUM: is constituted mostly of sebaceous secretion and 

other materials that are carried with it in its journey through 

a sebaceous duct and epidermal infundibulum to the skin 

surface, namely, squames, Pityrosporum ovale and orbicu-

lare, Staphylococcus epidermidis, Propionibacterium acnes, 

and Demodex .

SECRETION: is a process whereby a specific product is 

elaborated as a result of the activity of a gland. Secretion 

also may refer to any substance that is produced by the act 

of secreting. The major kinds of secretion are those that are 

discharged on an internal or external surface of the body (i.e., 

by way of an exocrine gland) and those that secrete hormones 

that are dispatched into blood and lymph (i.e., by way of an 

endocrine gland). The glands in skin produce secretions of 

different types, i.e., merocrine by eccrine glands, apocrine by 

apocrine glands, and holocrine by sebaceous glands. Mero-

crine, apocrine, and holocrine secretions are all exocrine.

SECRETORY: pertains to a process whereby a specific prod-

uct is elaborated by cells of a gland. Secretion and excretion 

are two processes by which cells extrude their products. If the 

extruded material is to be used by the organism, the process is 

called secretion; if the extruded material is waste, the process 

is called excretion. All three glands in skin, namely, eccrine, 

apocrine, and sebaceous, are secretory.

regard to benign verses malignant proliferations the silhouette 

reflects the biologic behavior. There are exceptions.

SCAR: a type of fibrosis that represents the end stage of an 
inflammatory process or the end result of a wound healing, 

that early in its course resulted in destruction of preexisting 

tissue, evolved through granulation tissue, and eventuated in 

fibroplasia. Formation of granulation tissue, the scaffold on 

which fibroplasia usually proceeds, is a sign that healing of 

the wound has commenced. Histopathologically, a scar rather 

early in its course is made up of altered bundles of collagen in 

conjunction with a marked increase in the number of fibro-

cytes, both of those elements being oriented mostly parallel 

to the skin surface, and in association with what seems to be 

an increase in the number of dilated venules aligned mostly 

perpendicular to that surface and in the amount of mucin. 

Years later, the number of fibrocytes is so markedly decreased 

that sometimes they are identifiable with difficulty. In con-

trast, a keloid is a type of fibrosis that consists of strikingly 

thickened, brightly eosinophilic, homogeneous-appearing 

collagen bundles disposed randomly and affiliated with an 

increased number of plump fibrocytes that parallel the long 

axis of the thickened bundles. A dermatofibroma is another 

type of fibrosis in which coarse collagen bundles and many 

fibrocytes are arranged haphazardly, sometimes being joined 

by siderophages and lipophages that signify extravasation in 

the dermis previously of erythrocytes secondary to trauma at 

that particular site. Other findings encountered commonly 

in a dermatofibroma are fibrocytes and/or histiocytes inter-

spersed between distinctly thickened bundles of collagen at 

the periphery of the lesion, acanthosis, and hyperpigmen-

tation of the epidermis. Normal skin markings tend to be 

effaced when those three forms of fibrosing inflammation, 

i.e., scars, keloids, and dermatofibromas, encroach severely 

on the papillary dermis and impinge on the epidermis.

SCLEROSIS: clinically, a condition of hardness of the skin 
and, histopathologically, a type of fibrosis characterized by 

near obliteration of boundaries between bundles of collagen, 

the result being the appearance of the bundles having become 

blended (“homogenization”) and by marked decrease in the 

number of fibrocytes. Sclerosis usually indicates that fibro-

plasia has been longstanding. Examples of sclerosis are the 

thickened papillary dermis of lichen sclerosus et atrophicus 

and much, or all, of the dermis of chronic radiation dermati-

tis. Morphea, other than the form of it confined to the upper 

part of the dermis and known as lichen sclerosus et atrophi-

cus, is not typified by sclerosis; collagen bundles in a lesion of 

morphea formed fully are crowded but, nonetheless, discrete. 

At that stage, fibrocytes in morphea are decreased in number.

“SEBACEOUS FOLLICLE”: refers to a vellus-hair follicle on 
a face characterized by a prominent epidermal infundibulum, 



Review  |  Dermatol Pract Concept 2015;5(2):1 15

surface for the purpose of sampling exophytic lesions such as 

verrucae, seborrheic keratoses, fibroepithelial polyps, mela-

nocytic nevi, and cherry hemangiomas. Some flat lesions of 

melanoma-in situ in sites like the tip of the nose and in Bow-

en’s disease and basal cell carcinomas are sometimes ame-

nable to the shave technique. Unfortunately, the procedure is 

abused when it is used to biopsy inflammatory diseases of all 

kinds, proliferations that are mostly endophytic, and elevated 

pigmented lesions suspected of being melanoma. These all-

too-common practices are to be deplored because they often 

harvest inadequate specimens that prevent histopathologists 

from using criteria effective for diagnosis, criteria that have 

been formulated on the basis of sections cut from satisfactory 

biopsy specimens taken by scalpel excision. This technique 

using a razor blade can be modified to perform saucerization 

which can provide satisfactory “biopsies” of pigmented and 

other lesions if used properly and selectively. (SEE RAZOR 

BLADE REMOVAL, SEE SAUCERIZATION)

SHEATH: denotes a structure that encloses or surrounds a 
body. In skin, most sheaths are composed of fibrous tissue, the 

most notable being the perifollicular connective tissue sheath 

that extends along the entire outer sheath to the base of the 

infundibular epidermis. The follicular sheath is separated by 

a basement membrane from the epithelial component of a 

follicle. Nerve fascicles in skin also are associated with three 

connective tissue sheaths, the epineurium, perineurium, and 

endoneurium.

SHELL OUT: describes a method whereby certain benign 
proliferations and cysts are eased from their housings with a 

scalpel or other instrument and transported to the skin sur-

face along a path formed by an artifactual cleft that developed 

between compressed encompassing fibrous tissue and normal 

skin or subcutaneous fat.

SIDEROPHAGE: a macrophage that has ingested iron.

SIGNET-RING CELL: describes a mucin producing adeno-
carcinomatous cell whose cytoplasm is filled completely with 

mucin and is distended by it. Mucin causes the nucleus to be 

compressed and displaced to the side of a cell, thereby caus-

ing the entire cell to resemble a signet ring. The signet part 

is the nucleus at the side of the cell, the ring portion is the 

cytoplasm at the periphery of the cell, and the space reserved 

to accommodate a finger is the mucin. Other proliferations 

have been said to have cells that simulate this appearance (i.e. 

signet ring cells in some melanomas).

SILHOUETTE: is a representation of the outline of some-
thing, usually filled in with black or another solid color. In 

the mind’s eye of a histopathologist, the contours of a prolif-

eration or a cyst can be filled in with solid colors and made 

into silhouettes. Observation of a proliferation at scanning 

SEGMENT: refers to two fundamentally different parts of 
a hair follicle, namely, the upper and the lower. The upper 

segment consists of isthmus. It does not participate in the 

ever-repeating cyclic changes of a follicle. The lower seg-

ment is made up of two parts, namely, the stem above and 

the bulb below. The lower segment undergoes characteristic 

morphologic and functional changes during a follicular cycle 

that are designated growing (anagen), involuting (catagen), 

and resting (telogen).

SEMANTICS: The meaning of a word, phrase, or text

SEPTA: refers usually to struts of connective tissue that 
divide a normal or pathologic structure into compartments, 

for example, fibrous septa that partition fat lobules of nor-

mal subcutaneous tissue, granulomatous and fibrotic septa 

that form fenestrations in subcutaneous fat of erythema 

nodosum, and fibrous septa that create units composed of 

clusters of proliferative apocrine cells and mucin in mucinous 

carcinoma.

SEPTAL PANNICULITIS: an inflammatory process in the 
panniculus adiposis in which, as viewed at scanning magnifi-

cation, the infiltrate of inflammatory cells is situated mostly 

in the septa rather than in the lobules. In many instances the 

overlap with lobular may make distinction difficult.

SERUM: is the fluid portion of the blood obtained after 
removal of the fibrin clot and blood cells, distinguished from 

plasma in circulating blood.

SESSILE: means attached by a base broad, in contrast to a 
polyp which is attached by a peduncle.

SHADOW CELLS: are ones cornified in which, as a conse-
quence of karyolysis, nuclei have faded but an outline vague 

of them still can be recognized. These cells represent attempts 

faulty at differentiation toward hair and are found only in 

conditions in which some follicular matrical cells are present, 

examples of that being panfolliculoma, pilomatricoma, matri-

coma, matrical carcinoma, desmoplastic trichoepithelioma, 

and mixed tumors with apocrine, follicular and sometimes 

sebaceous differentiation. Rarely, “shadows cells” may be 

present in trichoblastomas and trichoblastic (basal cell) 

carcinomas, both of those proliferations consisting mostly of 

germinative cells. “Shadow cells” tend to become calcified, a 

phenomenon that is visualized at first as sprinkling of delicate 

particles basophilic within corneocytes arranged compactly 

and later as obscuration complete of corneocytes by material 

homogeneous and purple. In pilomatricoma, “shadow cells” 

often act as a nidus for osseous metaplasia by fibrocytes.

SHAVE (TANGENTIAL, HORIZONTAL) BIOPSY TECH-
NIQUE: describes a procedure performed with a surgical 
blade or razor blade directed mostly parallel to the skin 



16 Review  |  Dermatol Pract Concept 2015;5(2):1

cystoadenomas are mostly cystic. Solid carcinoma designates 

a distinctive histopathologic variant of apocrine carcinoma.

SPECIMEN: designates a sample of tissue taken by a surgical 
procedure in preparation for examination by conventional 

microscopy in order to determine particular characteristics of 

it from which inferences (diagnoses) may be drawn. A distinc-

tion exists· between a specimen of skin removed by a surgical 

instrument from a person and sections of skin that represent 

slivers cut by a microtome from a specimen.

SPINDLE-SHAPED CELL: having the shape of a spindle, i.e., 
being like a stick with ends tapered used to form and twist 

yarn in spinning by hand. True spindle-shaped melanocytes 

are thin and are met with more often in melanoma than in 

the type of nevus paid heed most by Spitz in 1948 and in 

which large cells constituent tend to be fusiform, often in 

conjunction with ones round, plump oval, polygonal, and 

plasmacytoid; never do spindle-shaped melanocytes arrayed 

in fascicles monopolize in “classic” Spitz’s nevus, although 

they do predominate in what Spitz in 1948 referred as a 

“spindle cell tumor.” Last, it must be stressed that spindle-

shaped melanocytes do not qualify as “Spitz’s cells,” the sine 

qua non for which is cytoplasm copious; a true “spindle cell” 

of any kind, including one melanocytic, has cytoplasm paltry. 

In short, although spindle-shaped melanocytes may appear 

among “Spitz’s cells” in a “classic” Spitz’s nevi, they are not, 

in themselves “Spitz’s cells.” Thus “true” spindle shaped cells 

contrast with fusiform shaped cells, whether referring to the 

above or those found in other melanocytic nevi, including 

“blue nevus.”

SOLID CYSTIC: describes the two elements that constitute 
various proliferations, benign and malignant, one of them 

being made up of cells arranged compactly (solid) and of 

the other cells that line a sac containing fluid or material 

(cystic), the example quintessential of the phenomenon being 

one presentation histopathologic of apocrine (solid cystic) 

hidradenoma.

SPIR-: is a prefix used to convey a sense for relation to a 
structure that spirals. In dermatopathology, spir- traditionally 

has referred to the spiral of the component intraepidermal of 

an eccrine duct, i.e., to the acrosyringium, and perforce to 

proliferations thought to be eccrine in character. The terms 

eccrine spiradenoma and eccrine acrospiroma, however, are 

misnomers because both spiradenoma and some prolifera-

tions included under the rubric of acrospiroma (i.e., pale or 

clear-cell hidradenoma) show apocrine, rather than eccrine, 

differentiation. Because the segment distal of an apocrine duct 

spirals through infundibular epidermis, the concept and the 

word acrosyringium is applicable equally to the apocrine, as 

well as the eccrine duct.

magnification of a conventional microscope enables histopa-

thologists to imagine, among other things, its silhouette. The 

silhouette of a proliferation is the morphologic representation 

of the biological behavior of that proliferation. For example, 

a silhouette that is symmetric, vertically oriented, wedge-

shaped, and sharply circumscribed with smooth borders 

indicates that a proliferation, if primary in skin, is likely to 

be benign. A silhouette that is asymmetric, poorly circum-

scribed, and jagged in outline nearly always signifies that a 

proliferation, if primary in skin, is malignant. All too often, 

textbooks of general pathology emphasize cytologic details 

almost exclusively as criteria for differentiating benign from 

malignant proliferation, whereas, in actuality, features of 

silhouette are more compelling in regard to that distinction 

because they are more consistent morphologic reflections of 

biological behavior. In short, accurate diagnosis of cutaneous 

proliferation requires assessment of silhouette at scanning 

magnification and of cytologic features at higher magnifica-

tions. The entire range of magnifications, from scanning to 

high, is complementary in enabling a histopathologist to come 

to a specific, accurate diagnosis.

SINUS: an epithelium-lined channel in the skin that opens 
on the surface, usually through an infundibular ostium. In 

contrast to a fistula that is open on both ends, neither of 

which needs to be in continuity with an infundibulum, a sinus 

is open at one end only. Examples of a cutaneous sinus are 

seen in lesions of the so-called follicular occlusion triad, all 

of which begin as explosive suppurative infundibulitides/fol-

liculitides, namely, acne conglobata, hidradenitis suppurativa, 

and dissecting cellulitis of the scalp (to which should be added 

a fourth analogue, i.e., acne keloidalis). A sinus forms as a 

result of re-epithelialization of an infundibulum as it attempts 

to restore itself to its original state after having burst and 

ejected its contents, mostly of neutrophils, into the dermis, 

where those polymorphs are joined, in time, by histiocytes 

in company with lymphocytes and plasma cells, and, eventu-

ally, by fibrocytes. The failed attempt of an infundibulum to 

reconstitute itself in that setting is manifested as a sinus which 

invariably, is accompanied by fibrosis.

SINUS TRACT: (SEE SINUS)

SOLAR ELASTOSIS: elastotic material, i.e., the altered, blu-
ish, spaghetti-like connective tissue produced by fibrocytes 

that have been affected by sunlight over the course of decades. 

This is a sign of longstanding damage to the skin by the effects 

of ultraviolet light.

SOLID: designates a substance or tissue that is not fluid, 
gaseous, or hollow. The term is applied in dermatopathol-

ogy to proliferations that are neither tubular nor cystic. For 

example, poromas and cylindromas are mostly solid. Apo-

crine hidradenomas are solid and cystic. Apocrine papillary 



Review  |  Dermatol Pract Concept 2015;5(2):1 17

proliferations common, i.e., verruca vulgaris and seborrheic 

keratoses.

SQUAMOID CELLS: (SEE SQUAMOID)

SQUAMOUS EDDIES: are whorls made up of spinous cells 
mostly, but also of granular and cornified cells, that pre-

sumably come into being as a consequence of the spiral of 

sebaceous ducts through infundibular epidermis. The circum-

stance most common for development of “squamous eddies” 

is verruca vulgaris, and the next most common is seborrheic 

keratosis. Most of the time, “squamous eddies” are a sign of 

a benign condition and also of irritation of the lesion (i.e. 

seborrheic keratosis.)

STAGE: usually refers to the extent of spread of a malignant 
proliferation. Clinical stages for melanoma have been defined 

by the American Joint Committee on Cancer and the New 

York University Melanoma Cooperative Group. The value 

of these stagings is debatable by some.

STELLATE: shaped like a star, arranged in a roset or rosets.

STEM: describes the upper part of the lower segment of a 
follicle that resembles the stem of a flower, a slender stalk 

that derives from a bulb and that supports a “flower” (upper 

segment of isthmus and infundibular epithelium). The course 

of a stem is from Adamson’s fringe below to desquamation 

of corneocytes of the inner sheath above (from the top of 

the bulb to the base of the isthmus). In terminal follicles in 

anagen, the stem is the longest part.

STORIFORM: refers to a pattern created by the interweaving 
of fascicles of oval and spindle cells that causes it to resemble 

the intersecting intertwining pattern of a doormat.

STRAND: refers to epithelial and nonepithelial cells arranged 
in single file, in contrast to a cord, in which cells are arranged 

in rows of two, and columns, in which cells are arranged in 

formations more than two cells wide. Strands may be seen 

in benign conditions, such as melanocytes splayed in a single 

file between bundles of collagen of the reticular dermis in a 

superficial type of congenital nevus, and in malignant ones, 

such as metastatic carcinoma to the skin from a breast.

STRATIFIED SQUAMOUS EPITHELIUM: consists of cells 
of different shapes, i.e., columnar, cuboidal, and polygonal, 

that flattens progressively as they come nearer to the free sur-

face. Stratified squamous epithelium, such as the epidermis, 

may cornify completely and be free of nuclei in its outermost 

cells or, as in mucous membranes, may cornify partially and 

retain nuclei in its outermost cells.

STROMA: designates the connective tissue component of a 
proliferation of epithelial cells. It may be edematous, muci-

nous, or fibrous or it may contain globules of amyloid. Some 

SPITZOID: in general, any lesion that resembles histo-
pathologically a “classic” Spitz’s nevus. The term spitzoid 

melanoma has been applied to a melanoma that has some 

attributes histopathologic of that nevus.

SPITZ’S CELLS: melanocytes of the size and shape of those 
pictured in most photomicrographs by Spitz in her article 

seminal of 1948, they being ones of “classic” Spitz’s nevus 

and having a large nucleus, abundant cytoplasm, and round, 

fusiform, and polygonal shapes especially.

SPONGIFORM PUSTULE: a collection of neutrophils in 
the spinous and granular zones of the epidermis. Remnants 

of cell membranes give the pustule a sponge-like appearance.

SPONGIOSIS (Intercellular edema): of the epidermis and of 
epithelial structures of adnexa, expressed morphologically 

by widened spaces between spinous cells and by intercellular 

bridges that stretch across those extended spaces in company 

with a sprinkling of cells, usually inflammatory ones foreign 

normally to the epidermis. Although spongiosis nearly always 

is mediated by inflammatory cells, particularly by lympho-

cytes but sometimes by eosinophils and even by neutrophils, 

it may be induced by neoplastic lymphocytes, such as those 

of mycosis fungoides. In short, spongiosis is a distinctive pat-

tern of cutaneous epithelium brought into being usually by 

inflammatory cells and unusually by neoplastic ones. Some 

spongiotic inflammatory processes may eventuate in vesicles 

clinically, such as allergic contact dermatitis, nummular der-

matitis, dyshidrotic dermatitis, and “id” reactions, whereas 

others, such as seborrheic dermatitis, erythema annulare 

centrifugum, and pityriasis alba, do not progress to vesicles. 

Practically never does spongiosis in mycosis fungoides cul-

minate in a vesicle.

SPONTANEOUS: means self-generated, which is incompat-
ible with biologic processes. Therefore, all so-called sponta-

neous phenomena like spontaneous keloids and spontaneous 

regression of melanoma are not spontaneous at all. The 

former results from external trauma and the latter from the 

effects of lymphocytes on the melanocytes.

SQUAME: designates a lone corneocyte, particularly one that 
has become detached from its neighbors, as happens, com-

monly following rupture of an infundibular type of follicular 

cyst. In that circumstance, squames often are found free in the 

dermis or subcutaneous fat, or within multinucleate histio-

cytic giant cells. The term “squame” does not apply to physi-

ologic desquamation of clumps of epidermal corneocytes.

SQUAMOID: means resembling cells of the spinous zone of 
surface or the infundibular epidermis, in contrast to basaloid 

cells that look like basal cells of that epithelium. Proliferations 

of basaloid and squamoid cells are found together in some 



18 Review  |  Dermatol Pract Concept 2015;5(2):1

part of the reticular dermis. Capillaries from the superficial 

plexus loop into the dermal papillae.

SUPRAMATRICAL ZONE: designates the zone in a follicular 
bulb situated between the matrix below and the keratogenous 

zone above. It is bounded by the critical line at its base and by 

the B-fringe at its surface. Multiplication of cells that origi-

nated in the matrix has almost stopped by the time the supra-

matrical zone has been reached, in preparation for formation 

of hair. (SEE KERATOGENOUS ZONE, SEE B FRINGE)

SUPRAPAPILLARY PLATE: The portion of the epidermis 
situated immediately above the summit of dermal papillae.

SUPPURATION: Formation and exudation of pus, i.e., a 
creamy viscous fluid that consists of a daunting collection of 

neutrophils mostly, but also debris, both cellular and non-cel-

lular, that results from necrosis and degeneration consequent 

to the effects of destructive enzymes released from polymor-

phonuclear leukocytes. Accumulation of pus in a cavity of a 

cavernous organ is called empyema. Suppuration in skin may 

manifest itself as tiny pustules (i.e., Munro’s micro abscesses 

and Kogoj’s spongiform pustules) and as large abscesses (i.e., 

secondary to rupture of an infundibular cyst and in infectious 

processes, such as those caused by atypical mycobacteria and 

deep fungi). Within cutaneous epithelium, foci of suppuration 

may appear in both surface and infundibular epidermis, and 

in eccrine glands and ducts. Abscesses also may develop in the 

midst of the dermis or in the subcutaneous fat.

SYRINGO-: designates a tube such as is characteristic of 
some structures constituent of syringoma and of syringo-

matous carcinoma, but also of many other proliferations of 

character eccrine, apocrine, and sebaceous.

SYRINGOTROPISM: a biological phenomenon that indi-
cates growth or turning movement of a cell or a collection of 

cells toward an eccrine gland. In a strictly morphologic sense 

it is not definable. Adj. syringotropic.

The following terms would be better; intrasyringeal: placed 
within an eccrine gland; perisyringeal: present around an 

eccrine gland.

Syringotropic is not defined in medical dictionaries, or in 

textbooks of dermatopathology. However, it is constantly 

used in articles, especially in those about histopathology 

of mycosis fungoides. Strictly speaking, the suffix tropism 

implies movement, the best example being the turning or 

bending phenomenon that plants undergo in response to 

light as the environmental stimulus, called phototropism. 

Literally, syringotropism means a “turning toward the eccrine 

gland” or having an affinity for the eccrine gland respectively. 

A review of this word in the literature reveals a constant 

association with one condition only: mycosis fungoides. The 

proliferations may be associated with stroma copious, i.e., 

fibrofolliculoma/ trichodiscoma, trichoblastoma, and the 

fibroepitheliomatous type of trichoblastic (basal cell) carci-

noma, whereas other proliferations are accompanied by little 

or no stroma, i.e., cylindroma, sebaceoma, and infundibulo-

cystic trichoblastic (basal cell) carcinoma. Understanding of 

stroma can be very helpful in determining whether a lesion is 

benign or malignant.

STROMA LIKE THAT OF PERIFOLLICULAR SHEATH 
IN AN EMBRYO: refers to highly fibrocytic, richly vascular 
connective tissue made up chiefly of delicate fibrillary bundles 

of collagen in combination with mucin plentiful, the constel-

lation of findings being reminiscent of that seen around a 

follicle developing in an embryo.

SUBCORNEAL PUSTULE: a collection of neutrophils situ-
ated immediately beneath the cornified layer of the epidermis.

SUBCUTANEOUS: denotes being situated beneath the 
dermis and therefore beneath the skin. The skin itself con-

sists only of epidermis and dermis. The subcutaneous fat 

was known in times past as the hypodermis because it lies 

immediately beneath the skin. A distinction exists between 

subcutaneous fat and subcutaneous tissue. Subcutaneous 

fat consists predominantly of adipocytes. At the base of the 

subcutaneous fat is fascia, or aponeurosis, and beneath it sits 

skeletal muscle. Lesions that arise in or are situated in the 

dermis and subcutaneous fat are considered to be housed in 

superficial soft tissues, whereas those found below the fascia 

are regarded as being within deep soft tissues. Dermatopa-

thology overlaps with “soft tissue” pathology; although most 

regard it as a separate field of pathology.

SUPERFICIAL ATYPICAL MELANOCYTIC PROLIF-
ERATION OF UNCERTAIN SIGNIFICANCE (SAMPUS): 
a phrase employed for diagnosis by David Elder, his associ-

ates, and followers of them to designate a “category” that 

“includes predominantly junctional melanocytic prolif-

erations and melanocytic proliferations that are confined 

to the epidermis and papillary dermis, “without evidence of 

tumorigenic proliferation or mitotic activity there.” Because 

the term is generic, rather than specific, it is not a diagnosis 

precise but a description recondite and, at the same time, an 

acknowledgment of doubt about behavior biologic, adding 

nothing to what should be an effort with determination to 

arrive at a diagnosis with precision based on an understand-

ing profound of melanocytic proliferations. Now is the time 

to jettison that phrase fuzzy before it becomes yet another 

example of gobbledygook in the language of general pathol-

ogy and dermatopathology.

SUPERFICIAL VASCULAR PLEXUS: refers to venules and 
arterioles situated beneath the papillary dermis in the upper 



Review  |  Dermatol Pract Concept 2015;5(2):1 19

are described by words that finish with tropism or tropic is 

that dermatopathologists use these words only for malignant 

conditions. Confronted with exactly the same morphologic 

finding, namely, lymphocytes in eccrine glands, syringotro-

pism is used only after having decided already on a malignant 

condition, usually mycosis fungoides. When the diagnosis of 

a benign condition, i.e., lupus erythematosus or neutrophilic 

hidradenitis, is made the cell infiltrates are not termed tropic.

In addition, the term seems only to apply to lymphocytes, not 

eosinophils or neutrophils.

SYSTEMATIC: concerning a system or organized according 
to a system.

SYSTEMIC: pertinent to a whole body rather than to one of 
its parts; somatic.

SYSTEMIZATION: the process of organizing something 
according to plan.

SYSTEMATIZED: arranged according to an organized 
system.

words syringotropism and syringotropic are employed in the 

cases of mycosis fungoides in which neoplastic lymphocytes 

are found in the epithelia of eccrine glands. In fact, this cri-

terion has led to two subtypes of mycosis fungoides, namely, 

the so-called syringotropic and folliculotropic. (SEE FOL-

LICULOTROPISM)

There are only occasional exceptions in the usage of these 

words in reference to entities other than mycosis fungoi-

des, but interestingly nearly all are malignant: melanoma, 

bowenoid carcinoma, skin metastases of other carcinomas, 

etc. Occasionally, syringotropic is used for an inflammatory 

disease.

What dermatopathologists intend to describe by the word 

syringotropic is the biopsies in which lymphocytes are placed 

mostly in the eccrine units, i.e., those specimens in which cells 

have a clear affinity for these adnexa. But this is not exclu-

sive of mycosis fungoides. Many other diseases, much more 

common and benign, display cells with tendency for adnexa. 

Examples are neutrophilic hidradenitis or lichen striatus to 

mention but some of them. The reason why none of these