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Quiz  |  Dermatol Pract Concept 2015;5(2):15 83

DERMATOLOGY PRACTICAL & CONCEPTUAL
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The patient

A 65-year-old Caucasian man presented to our clinic with 

a 10-year history of a slow-growing, painful nodular lesion 

on the right thigh that was sensitive to cold. The physical 

examination revealed a well-defined, smooth, purple nod-

ule, 7 mm in diameter, with a peripheral brown rim (Fig-

ure 1). The lesion was tender to light touch. Dermoscopy 

disclosed a multicolored structureless pattern: a purple 

center surrounded by a whitish area and an outer brown 

pigmentation (Figure 2). An excisional biopsy of the lesion 

was performed. Further histopathological examination 

revealed intradermal sheets of monomorphic round cells, 

interrupted by enlarged vessels with varying size (Figure 

3, hematoxylin-eosin, x40). A fibrous pseudocapsule sur-

rounding sheets of cells with an eosinophilic cytoplasm and 

central nuclei was also seen (Figure 4, hematoxylin-eosin, 

x100). Immunohistochemically, tumor cells were reactive 

for smooth muscle actin (Figure 5).

Painful purple nodule on the right thigh
André Oliveira1, Susana Brás1, Adelaide Milheiro2, Jorge Cardoso1

1 Department of Dermatology, Hospital de Curry Cabral—Centro Hospitalar de Lisboa Central, Lisboa, Portugal
2 Department of Pathology, Hospital de Curry Cabral—Centro Hospitalar de Lisboa Central, Lisboa, Portugal

Citation: Oliveira A, Brás S, Milheiro A, Cardoso J. Painful purple nodule on the right thigh. Dermatol Pract Concept 2015;5(2):15. 
http://dx.doi.org/10.5826/dpc.0502a15

Copyright: ©2015 Oliveira 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.

Corresponding author: André Oliveira, MD, Department of Dermatology, Hospital de Curry Cabral—Centro Hospitalar de Lisboa Central, 
Rua da Beneficência nº8, 1069-166, Lisboa, Portugal. Tel. +35 1912561666; Fax. +35 1217924392. E-mail: andre.oliveira@sapo.pt

Figure 1. A well-defined, smooth, purple nodule, 7 mm in diameter, 
with a peripheral brown rim. [Copyright: ©2015 Oliveira et al.]

Figure 2. Dermoscopy: a multicolored structureless pattern, a purple 
center surrounded by a whitish area and an outer brown pigmenta-
tion. [Copyright: ©2015 Oliveira et al.]



84 Quiz  |  Dermatol Pract Concept 2015;5(2):15

What is your diagnosis?
Please send your answer to dpc@derm101.com. The first cor-

rect answer will receive a DL3N hand dermoscope [cordially 

sponsored by 3GEN]. The case and the answer to the question 

will be presented in the next issue of Dermatology Practical 

& Conceptual.

Figure 3. Histopathological examination revealed intradermal 
sheets of monomorphic round cells, interrupted by enlarged vessels 
with varying size. [Copyright: ©2015 Oliveira et al.]

Figure 4. Histopathological examination revealed a fibrous pseudo-
capsule surrounding sheets of cells with an eosinophilic cytoplasm 
and central nuclei. [Copyright: ©2015 Oliveira et al.]

Figure 5. Tumor cells were reactive for smooth muscle actin. [Copy-
right: ©2015 Oliveira et al.]