Dermatology: Practical and Conceptual


Image Letter  |  Dermatol Pract Concept 2020;10(2):e2020038 1

Dermatology Practical & Conceptual

Case Presentation

A male patient, 72 years old, had a history of melanoma 

(AJCC stage IB) located on the left leg. During a regular fol-

low-up visit, we observed an asymmetric, brown, blue-gray 

plaque with 1.2 cm maximum diameter, sharply delimited 

on the right supraclavicular region. On dermoscopy, the 

lesion presented a multicomponent pattern, with 4 colors 

(brown, gray, blue, and white), a globular atypical pattern, 

pseudonetwork, and asymmetrical globules. In the left area 

of the image, it was possible to see a homogenous brown 

area, with overlapping gray and white shiny structures and 

ovoid nests which led to the suspicion of a collision tumor of 

seborrheic keratosis and basal cell carcinoma or melanoma, 

mainly because of these two distinctive patterns on the same 

area (Figure 1). The lesion was excised, and the histology was 

compatible with a seborrheic keratosis.

Teaching Point

At times, the clinical and dermoscopic diagnosis of seborrheic 

keratosis is challenging because it can mimic other conditions 

including basal cell carcinomas or melanomas [1,2].

References

1. Mansur AT, Yildiz S. A diagnostic challenge: inflamed and pigment-

ed seborrheic keratosis. Clinical, dermoscopic, and histopathologi-

cal correlation. Dermatol Online J. 2019 Mar 15;25(3). pii: 13030/

qt0w56m5hq.

2. Carrera C. The many faces of seborrheic keratosis. Actas Dermo-

sifiliogr. 2019;110(5):338.

When Seborrheic Keratosis Is Wearing a Mask
Cristina Sousa,1,2 Sebastian Podlipnik,1 Susana Puig,1 Josep Malvehy1

1 Dermatology Department, Hospital Clínic, Barcelona, Spain

2 Dermatology Department, Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal

Key words: seborrheic keratosis, fusion tumor, dermoscopy, dermatology challenge

Citation: Sousa C, Podlipnik S, Puig S, Malvehy J. When seborrheic keratosis is wearing a mask. Dermatol Pract Concept. 
2020;10(2):e2020038. DOI: https://doi.org/10.5826/dpc.1002a38

Accepted: January 18, 2020; Published: April 20, 2020

Copyright: ©2020 Sousa 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.

Authorship: All authors have contributed significantly to this publication.

Corresponding author: Ana Cristina da Silva Sousa, Rua Conceição Fernandes, 4434-502 Vila Nova de Gaia, Portugal. Email: a.cristina.
silvasousa@gmail.com

Figure 1. Dermoscopy image of a cutaneous lesion present-

ing with a multicomponent pattern, with 4 colors, a globular 

atypical pattern, pseudonetwork, and asymmetrical globules.

https://doi.org/10.5826/dpc.1002a38
mailto:a.cristina.silvasousa@gmail.com
mailto:a.cristina.silvasousa@gmail.com