DERMATOLOGY PRACTICAL & CONCEPTUAL
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Quiz | Dermatol Pract Concept 2012;2(2):5 21

The patient

A 48-year-old woman presented herself with an erythema-

tous macule on the extensor surface of the right thigh. The

lesion had been present for years, but recently the patient

noticed some increase in size and changes in the coloration.

This had prompted her to see a dermatologist (Figure 1).

A biopsy was taken and photomicrographs are presented in

Figures 2A-I. What is your diagnosis?

Answer and explanation

Hobnail lymphatic malformation (so-called hobnail heman-

gioma or targetoid hemosiderotic hemangioma)

Dilated and bizarre-shaped vessels are seen in the upper

reticular dermis and extend into the papillary dermis. At the

periphery of the lesion vessels are smaller in diameter and

assume slit-like configurations between collagen bundles

reminiscent of the macular stage of Kaposi’s disease. At

From the Dermatologikum Hamburg: Quiz
Almut Böer-Auer, M.D.1

1 Dermatologikum Hamburg, Hamburg, Germany

Citation: Böer-Auer A. From the Dermatologikum Hamburg: Quiz. Dermatol Pract Conc. 2012;2(2):5. http://dx.doi.org/10.5826/
dpc.0202a05.

Copyright: ©2011 Böer-Auer. 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: Almut Böer-Auer, M.D., Dermatologikum Hamburg, Drehbahn 1-3, 20354 Hamburg, Germany. Tel. +49. 40.
3510750. Email: boer@dermatologikum.de.

mailto:

22 Quiz | Dermatol Pract Concept 2012;2(2):5

A B C

higher magnification, the vessels are seen to be lined by a

single layer of endothelial cells with plump nuclei. Nuclei

have a typical hobnail appearance in some vessels, whereas

others show what has been described as a matchstick mor-

phology. In some foci, papillary projections protrude into the

lumen of a vessel.

The lesion is covered by a broad zone of parakeratosis.

Numerous extravasated erythrocytes are present between

collagen bundles. A sparse infiltrate of lymphocytes, histio-

cytes, and few plasma cells is also present. Iron stain high-

lights numerous hemosiderophages (Figure 3).

In clinicopathological correlation, the findings seen in

this patient are stereotypical of a fully developed lesion of

so-called hobnail lymphatic malformation (HLM) (formerly

called hobnail hemangioma or targetoid hemosiderotic

hemangioma). The targetoid appearance seen clinically is

explained by the hemorrhage and the hemosiderin deposits

that form a halo around the angioma.

HLM arises commonly on the extremities and trunk and

lesions are usually less than 1 cm in diameter. The clinical

presentation is not always as characteristic as seen here.

Studies on larger series of patients have shown that often

lesions present as angiomatous macule or papule without

any halo [1-3]. This variation has been interpreted as dif-

ferent stages in the process of evolution and devolution of

the lesion, as result of hormonal influences, or as a result

of previous trauma to a preexisting angioma. In the case

shown here, the broad zone of parakeratosis indicates that

the lesion has, in fact, been irritated from the outside.

The clinical variation of the lesion is reflected in the num-

ber of different diseases that have been considered as clini-

cal differential diagnoses of patients reported in the literature

[1-3]. It includes such conditions as disparate as melanocytic

lesions, infantile hemangioma, tufted angioma, Kaposi sar-

coma, insect bites, erythema multiforme, and dermatofibroma.

Not only clinically but also histopathologically HLM

shows some variation. Mentzel et al studied 62 cases and

described a biphasic growth pattern of dilated vessels lined

by hobnail endothelial cells in superficial parts of the lesion

and collagen dissecting narrow vessels in deeper parts of the

lesion. Some lesions resembled cavernous lymphangioma or

lymphangioma circumscriptum, others had features reminis-

cent of retiform hemangioendothelioma, progressive lymph-

angioma and so-called Dabska’s tumor [3]. Late lesions have

been described as showing collapsed vascular lumina, fibro-

sis, and abundant hemosiderin [3].

Quiz | Dermatol Pract Concept 2012;2(2):5 23

It is important to note that hobnail endothelial cells are

not unique to hobnail angioma but may also be seen in reti-

form hemangioendothelioma, progressive lymphangioma,

and papillary intralymphatic angioendothelioma. But the

most important differential diagnosis of HLM is the macular

stage of Kaposi’s disease. The promontorium sign, slit-like

proliferations of capillaries, hemorrhage, hemosiderophages,

and infiltrates containing plasma cells can be seen in both

conditions [2-5]. However, intraluminal papillary projections

and hobnail appearance of endothelial cells is usually not

seen in Kaposi’s disease and vessel proliferations of a macu-

lar stage of Kaposi’s disease almost always spare the papil-

lary dermis, whereas hobnail angioma typically involves the

papillary dermis. Moreover, lesions of Kaposi’s disease are

usually positive for human herpesvirus type 8.

The condition presented here was first described in 1988

by Santa Cruz and Aronberg. They recognized it as a dis-

tinctive entity and characterized it clinically and histopath-

ologically [1]. They were impressed by the clinical appear-

ance, which was targetoid in all of their cases and termed it

“targetoid hemosiderotic hemangioma.” The term “hobnail

hemangioma” was introduced in 1999 by Guillou et al, who

attempted to emphasize the histopathological hallmark of

the condition, namely, endothelial cells shaped like hobnails

and matchsticks [2].

HLM is conventionally classified as a benign vascular

tumor, but it has been a matter of controversy whether it

can be differentiated from blood vessels or lymphatics and

whether it is a true neoplasm or a malformation. Franke et

al, in 2004, showed that endothelia of hobnail hemangio-

mas exhibit an antigenic profile similar to normal lymphat-

ics, the majority of neoplastic vascular channels expressing

CD31 but not CD34 and lacking pericytes [4]. Moreover, the

lymphatic endothelial cell marker D2-40 (podoplanin) was

strongly positive in all lesions studied by them. Therefore,

they suggested that what had been called hobnail hemangi-

oma really was a lymphangioma and that naming it “hemo-

siderotic angioma” or “hemosiderotic cutaneous lymphan-

gioma“ would be more appropriate [4].

Very recently, in January 2012, immunostaining with the

endothelial marker Wilms tumor 1 (WT1) has been investi-

gated in larger series of the tumor and has illuminated the

nature of it. WT1 is considered to be expressed by vascular

neoplasms but not by malformations. Trindade and cowork-

ers studied 52 cases of HLM and none of them expressed

WT1. In 10 of their cases, the authors also performed other

stainings and found lesions to be positive with D2-40 and

negative with Ki-67 and human herpesvirus 8 latent nuclear

antigen. The authors concluded that these results supported

a lymphatic line of differentiation, but because of WT1 nega-

tivity it should be classified as a lymphatic malformation.

They suggested the term “superficial hemosiderotic lym-

phatic malformation’’ for the condition [5].

At the same time, Al Dhaybi et al investigated 12 pediatric

cases of HLM with almost the same set of immunohistochem-

ical markers. They found D2-40 immunostaining to be posi-

tive in all cases, while WT1 was largely negative. The authors

also concluded that hobnail hemangioma should be classified

as lymphatic vascular malformation and proposed the name

“targetoid hemosiderotic lymphatic malformation” [6].

In short, what has been described as hobnail hemangi-

oma (or targetoid hemosiderotic hemangioma) has recently

been shown to be a lymphatic malformation based on immu-

nohistochemical staining characteristics. That is why, here,

we replaced the former term hobnail hemangioma with the

term hobnail lymphatic malformation.

References

1. Santa Cruz DJ, Aronberg J. Targetoid hemosiderotic hemangio-

ma. J Am Acad Dermatol. 1988;19(3):550-8.

2. Guillou L, Calonje E, Speight P, Rosai J, Fletcher CD. Hobnail

hemangioma: a pseudomalignant vascular lesion with a reap-

praisal of targetoid hemosiderotic hemangioma. Am J Surg

Pathol. 1999;23(1):97-105.

3. Mentzel T, Partanen TA, Kutzner H. Hobnail hemangioma

(“targetoid hemosiderotic hemangioma”): clinicopathologic

and immunohistochemical analysis of 62 cases. J Cutan Pathol.

1999;26(6):279-86.

4. Franke FE, Steger K, Marks A, Kutzner H, Mentzel T. Hobnail

hemangiomas (targetoid hemosiderotic hemangiomas) are true

lymphangiomas. J Cutan Pathol. 2004;31(5):362-7.

5. Trindade F, Kutzner H, Tellechea O, Requena L, Colmen-

ero I. Hobnail hemangioma reclassified as superficial lym-

phatic malformation: a study of 52 cases. J Am Acad Dermatol.

2012;66(1):112-5. Epub 2011 Aug 6.

6. Al Dhaybi R, Lam C, Hatami A, Powell J, McCuaig C, Kokta V.

Targetoid hemosiderotic hemangiomas (hobnail hemangiomas)

are vascular lymphatic malformations: a study of 12 pediatric cas-

es. J Am Acad Dermatol. 2012;66(1):116-20. Epub 2011 Jul 27.