Dermatology: Practical and Conceptual


DERMATOLOGY PRACTICAL & CONCEPTUAL
www.derm101.com

Observation  |  Dermatol Pract Concept 2012;3(2):10 63

Report of a case

A 60-year-old male presented with a solitary, asymptomatic, 

erythematous annular plaque on the medial portion of his 

right distal leg. Clinically, the lesion had central atrophy 

with peripheral hyperpigmentation, elevation and scaling 

(Figure 1). The differential diagnosis at clinical examination 

included: granuloma annulare, angular lichen planus, hyper-

trophic tinea corporis, and pigmented Bowen’s disease.

Dermatoscopic imaging with polarized light demon-

strates a non-chaotic lesion. There were two basic patterns; 

a central structureless and peripheral brown, thick, curved 

lines. Scattered red dots were found in the periphery, these 

correspond to pin point or coiled blood vessels. (Figure 2). 

Clues for a dermatofibroma include the central hypopig-

mentation and structureless pattern. There is a single clue 

for Bowen’s disease; a structureless pattern. There are three 

clues suggestive of a lichenoid keratosis; brown thick curved 

lines; central structureless, and peripheral red dots. The dif-

ferential diagnosis of a lichenoid keratosis supersedes that of 

a seborrheic keratosis because the peripheral red dots and 

structureless pattern indicate that there is an inflammatory 

process suggestive of central regression. Although lichenoid 

keratosis is a likely diagnosis, dermatoscopic examination is 

diagnostically inconclusive. Further visualization is needed 

to rule out pigmented Bowen’s disease.

Lichenoid keratosis: non-invasive imaging in the 
setting of diagnostic uncertainty
Marigdalia K. Ramirez-Fort*, M.D. 1, Samer Al Jalbout, M.D. 2, 

Harald Kittler, M.D. 3, Giovanni Pellacani, M.D. 2

1  Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
2  Department of Dermatology, University of Modena and Reggio Emilia, Modena, Italy
3  Department of Dermatology, Vienna University Hospital, Vienna, Austria

Key words: lichenoid keratosis, dermatoscopy, reflectance confocal microscopy, non-invasive imaging

Citation: Ramirez-Fort MK, Al Jalbout S, Kittler H, Pellacani G. Lichenoid keratosis: non-invasive imaging in the setting of diagnostic 
uncertainty. Dermatol Pract Conc. 2013;3(2):10. http://dx.doi.org/10.5826/dpc.0302a10.

Received: July 1, 2012; Accepted: March 1, 2013; Published: April 30, 2013

Copyright: ©2013 Ramirez-Fort et al. 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.

Funding: None.

Competing interests: The authors have no conflicts of interest to disclose.

All authors have contributed significantly to this publication.

Corresponding author: Marigdalia K. Ramirez-Fort, M.D., Center for Clinical Studies, 6655 Travis St, Suite 120, Houston, TX, USA. Tel. 
E-Mail: mramirez-fort@ccstexas.com.

Figure 1. Gross features at presentation. There is central atrophy, 

with peripheral hyperpigmentation, elevation and scaling. [Copy-

right: ©2013 Ramirez-Fort et al.]



64 Observation  |  Dermatol Pract Concept 2012;3(2):10

reflective dots, called “plump-bright cells” within the islands; 

these cells correspond to melanophages and are associated 

with inflammation (Figure 5). Other small bright particles 

are seen in the papillary dermis and correspond to leuko-

cytes. These mentioned findings are seen in lichenoid kera-

toses, i.e., seborrheic keratoses under regression. There is 

minimal concern for pigmented Bowen’s disease, where one 

would expect to see architectural disruption of the epidermis 

and cellular pleomorphism.

Histopathology of the lesion revealed a seborrheic ker-

atosis-clonal type. Figures 6A and 6B demonstrate classic 

findings of a seborrheic keratosis, including focal areas of 

Imaging by confocal microscopy reveals a regular epi-

dermal architecture as well as islands of acanthosis; these 

islands correspond to densely packed round to polymor-

phous papillae and/or cord-like rete ridges at the dermoepi-

dermal junction (Figure 3). There is a well-contoured regu-

lar honeycomb pattern, indicating pigmented keratinocytes. 

These pigmented keratinocytes within the acanthotic islands 

correspond to the thick brown curved lines visualized with 

dermatoscopy. No papilla were discernable, also consis-

tent with an epidermal neoplasm (i.e., seborrheic keratosis) 

blunting the regular contour of the dermal-epidermal junc-

tion (Figure 4). One can also appreciate numerous hyper-

Figure 2. Dermatoscopic features (DermLite Foto) visualized with 

polarized light at 10x magnification. Two patterns are seen: central 

structureless (arrow) and peripheral brown thick, curved lines (ar-

rowhead). Scattered red dots are found in the periphery (asterisk). 

[Copyright: ©2013 Ramirez-Fort et al.]

Figure 3. Confocal microscopic features demonstrated with Viva-

scope 1500: bright, cord-like rete ridges and edged dermal papillae. 

[Copyright: ©2013 Ramirez-Fort et al.]

Figure 4. Confocal microscopic features demonstrated with Viva-

scope 1500: area displaying epidermal bulbous projections and 

keratin-filled invaginations. [Copyright: ©2013 Ramirez-Fort et al.]

Figure 5. Confocal microscopic features demonstrated with Viva-

scope 1500: inflammatory infiltrate in the papillary dermis. Plump-

bright cells correspond to melanophages. [Copyright: ©2013 

Ramirez-Fort et al.]



Observation  |  Dermatol Pract Concept 2012;3(2):10 65

not all neoplastic processes are pigmented, which minimizes 

the clinical specificity in atypical presentations. Reflectance 

confocal microscopy (RCM) is particularly useful in these 

situations. By measuring reflectance, RCM highlights meta-

bolically active cells, i.e., pigmented, immune and neoplastic 

cells (independent of pigmentation), with inherently high 

interface refraction.

Clinical uncertainty is typically an indication for a biopsy. 

By improving the clinical utility of non-invasive imaging 

modalities, dermatologists are now able to curtail biopsy-

associated morbidity by achieving diagnostic certainty with 

non-invasive modalities. Dermatoscopy and RCM allow for 

a stepwise diagnostic approach—to progressively increase 

resolution of a lesion until diagnostic confidence is achieved. 

In this case presentation, we clearly demonstrate the utility of 

dermatoscopy and RCM in making the diagnosis of a lichen-

oid keratosis, which was further confirmed with histology.

References

1. Zaballos P, Blazquez S, Puig S, et al. Dermoscopic pattern of in-

termediate stage in seborrhoeic keratosis regressing to lichenoid 

keratosis: report of 24 cases. Br J Dermatol. 2007;157(2):266-72.

2. Zaballos P, Salsench E, Serrano P, Cuellar F, Puig S, Malve-

hy J. Studying regression of seborrheic keratosis in lichenoid 

keratosis with sequential dermoscopy imaging. Dermatology. 

2010;220(2):103-9.

acanthosis, invaginations and elongation of the rete ridges 

in addition to hyperkeratosis and parakeratosis in the stra-

tum corneum. Additionally, a few proliferations of sharply 

demarcated intraepithelial nests of basaloid cells are seen, 

which sub-categorize the lesion into clonal type. In the der-

mis, there is a lichenoid inflammatory infiltrate, marking the 

regression of a seborrheic keratosis. The diagnosis is that of 

a lichenoid keratosis (LK).

Discussion

Here we present the step-wise approach of diagnosing a 

lichenoid keratosis in the setting of clinical uncertainty. The 

diagnosis of a seborrheic keratosis is typically made clini-

cally. However, states of irritation or regression (in which 

the seborrheic keratosis is termed a lichenoid keratosis) may 

mask a clear clinical diagnosis. In these situations, sebor-

rheic keratoses may be mistaken for melanocytic lesions, 

making the differentiation from melanoma, Bowen’s disease 

or superficial basal cell carcinoma challenging on both clini-

cal and dermatoscopic levels [1,2]. Zaballos et al has clearly 

established dermatoscopy as a useful tool to assists in the 

correct clinical recognition of LK and track the pathogenesis 

of these tumors by demonstrating the intermediate stages of 

epidermal regression. Much of clinical diagnosis is dependent 

on characteristic changes in pigment and texture. However, 

Figure 6. Histopathological features: (A) Epidermal basket-weave orthohyperkeratosis, keratotic plugs composed of parakeratotic cells, and 

focal vacuolar changes within the basal layer is seen (hematoxylin & eosin, 30x). (B) Close-up view of another area at the periphery of the 

lesion reveals clusters of melanophages in papillary dermis, directly beneath the dermoepidermal junction (hematoxylin & eosin, 200x). 

[Copyright: ©2013 Ramirez-Fort et al.]

A B