Dermatofibroma simulating seborrheic keratosis dermoscopically* * Work carried out at the Universidade de Pernambuco (UPE) - Recife (PE), Brazil.

Daniel Holanda Barroso Camila Pinon Zoby Leite Gabriela Diniz de Souza Araujo Márcia Almeida Galvão Teixeira Eliane Ruth Barbosa Alencar Silvana Maria de Morais Cavalcanti About the authors

Abstract:

Dermatofibroma is a frequent benign tumor of easy clinical diagnosis in most cases, but that can mimic other dermatoses. Dermoscopy may help to define the diagnosis and its classical pattern is a central white area, similar to a scar, surrounded by a discrete pigment network. However, dermoscopic findings are not always typical. We describe here a case of dermatofibroma exhibiting ridges, furrows and pseudocomedos, a pattern which is typical of seborrheic keratosis, in dermoscopy.

Keywords:
Dermoscopy; Histiocytoma, benign fibrous; Keratosis, seborrheic

INTRODUCTION

Dermatofibroma is a frequent benign cutaneous neoplasm that fits the group of fibrohistiocytic skin tumors.11 Hügel H. Fibrohistiocytic skin tumors. J Dtsch Dermatol Ges. 2006;4:544-55. Most of the time the diagnosis is clinical, although it may simulate other dermatoses.11 Hügel H. Fibrohistiocytic skin tumors. J Dtsch Dermatol Ges. 2006;4:544-55.

Dermoscopy is an auxiliary method with diagnostic criteria described for several skin lesions.22 Kilinc Karaarslan I, Gencoglan G, Akalin T, Ozdemir F. Different dermoscopic faces of dermatofibromas. J Am Acad Dermatol. 2007;57:401-6. In its classical forms, the dermoscopic differentiation between seborrheic keratosis and dermatofibroma is not difficult: the former shows the pattern of ridges and furrows33 Lin J, Han S, Cui L, Song Z, Gao M, Yang G, et al. Evaluation of dermoscopic algorithm for seborrhoeic keratosis: a prospective study in 412 patients. J Eur Acad Dermatol Venereol. 2014;28:957-62. and the latter, the white scar surrounded by discrete pigment network.22 Kilinc Karaarslan I, Gencoglan G, Akalin T, Ozdemir F. Different dermoscopic faces of dermatofibromas. J Am Acad Dermatol. 2007;57:401-6.,33 Lin J, Han S, Cui L, Song Z, Gao M, Yang G, et al. Evaluation of dermoscopic algorithm for seborrhoeic keratosis: a prospective study in 412 patients. J Eur Acad Dermatol Venereol. 2014;28:957-62. Nevertheless, the findings may also be atypical and, in these cases, histopathological confirmation is required.11 Hügel H. Fibrohistiocytic skin tumors. J Dtsch Dermatol Ges. 2006;4:544-55. A case of dermatofibroma simulating seborrheic keratosis dermoscopically is here presented.

CASE REPORT

A female patient mentioned a pruritic lesion on right calf. On physical examination, a hardened tumor measuring 1.5 x 1 cm with hyperchromic surface was found (Figure 1). Clinically, the hypotheses of simple chronic lichen and dermatofibroma were suggested. The dermoscopy revealed a pattern of ridges and furrows accompanied by pseudocomedos, compatible with seborrheic keratosis (Figure 2). Histopathologic examination showed a dermal tumor composed of fusiform cells, blood vessels and foamy histiocytes. The upper dermis was not affected by cellular proliferation (Figures 3 and 4). The epidermis was acanthotic, hyperkeratotic and with keratin-filled invaginations (Figure 3).

Figure 1
Elevated lesion measuring 1.5 x 1 cm on right calf

Figure 2
Dermoscopy showing pattern of ridges, furrows and pseudocomedos (arrow points)

Figure 3
Presence of fusocelular skin tumor sparing the upper dermis. The epidermis shows acanthosis, hyperkeratosis and kera tin-filled invaginations (asterisk) (hematoxylin-eosin, x40)

Figure 4
Many of the neoplastic cells present cytoplasm of foamy aspect (arrow points). Hematoxylin-eosin, x400

DISCUSSION

Typically, the dermatofibroma is an erythematous-brownish tumor of less than 1 cm and, most of the time, with a clinical diagnosis.11 Hügel H. Fibrohistiocytic skin tumors. J Dtsch Dermatol Ges. 2006;4:544-55. However, it may be confused with Spitz nevus, melanocytic composed nevus, melanoma and hemangioma.11 Hügel H. Fibrohistiocytic skin tumors. J Dtsch Dermatol Ges. 2006;4:544-55. In the described case, after macroscopic evaluation, the diagnoses of dermatofibroma and simple chronic lichen were suggested.

Even with the use of dermoscopy, diagnosis of dermatofibroma may be a challenge. Its classical dermoscopic appearance is that of a white area similar to a scar surrounded by a discrete pigment network.22 Kilinc Karaarslan I, Gencoglan G, Akalin T, Ozdemir F. Different dermoscopic faces of dermatofibromas. J Am Acad Dermatol. 2007;57:401-6. Zaballos et al., in a large series of cases, described ten dermoscopic patterns associated with this diagnosis.44 Zaballos P, Puig S, Llambrich A, Malvehy J. Dermoscopy of dermatofibromas: a prospective morphological study of 412 cases. Arch Dermatol. 2008;144:75-83. The classical pattern is the most common, present in 34% of the cases.44 Zaballos P, Puig S, Llambrich A, Malvehy J. Dermoscopy of dermatofibromas: a prospective morphological study of 412 cases. Arch Dermatol. 2008;144:75-83. Other common patterns are the discrete pigment network in all the lesion (14%) and the discrete pigment network with a white central area (9%). Nevertheless, in 6% of the cases, the dermatofibroma presents an atypical pattern44 Zaballos P, Puig S, Llambrich A, Malvehy J. Dermoscopy of dermatofibromas: a prospective morphological study of 412 cases. Arch Dermatol. 2008;144:75-83. and may simulate lentigo, blue nevus, melanoma and non-melanocytic lesions.22 Kilinc Karaarslan I, Gencoglan G, Akalin T, Ozdemir F. Different dermoscopic faces of dermatofibromas. J Am Acad Dermatol. 2007;57:401-6.

Dermoscopy of the lesion presented a pattern of ridges and furrows, classical of pigmented seborrheic keratosis22 Kilinc Karaarslan I, Gencoglan G, Akalin T, Ozdemir F. Different dermoscopic faces of dermatofibromas. J Am Acad Dermatol. 2007;57:401-6., despite its low specificity (43%)33 Lin J, Han S, Cui L, Song Z, Gao M, Yang G, et al. Evaluation of dermoscopic algorithm for seborrhoeic keratosis: a prospective study in 412 patients. J Eur Acad Dermatol Venereol. 2014;28:957-62. ; it may be observed in other dermatoses, like dermatofibroma.22 Kilinc Karaarslan I, Gencoglan G, Akalin T, Ozdemir F. Different dermoscopic faces of dermatofibromas. J Am Acad Dermatol. 2007;57:401-6. In addition, pseudocomedos could be found, which have 91% specificity for the diagnosis of seborrheic keratosis.33 Lin J, Han S, Cui L, Song Z, Gao M, Yang G, et al. Evaluation of dermoscopic algorithm for seborrhoeic keratosis: a prospective study in 412 patients. J Eur Acad Dermatol Venereol. 2014;28:957-62. Such dermoscopic findings associated with the absence of a classical dermatofibroma pattern would be sufficient to define the diagnosis of seborrheic keratosis. However, from a clinical point of view, the lesion was not compatible with this diagnosis and consequently our option was to withdraw it.

The histopathologic examination revealed a dermal tumor of fusiform cells and histiocytes, consistent with dermatofibroma.11 Hügel H. Fibrohistiocytic skin tumors. J Dtsch Dermatol Ges. 2006;4:544-55. The epidermis was acanthotic, hyperkeratotic and with keratin-filled invaginations. These findings of epidermis hyperplasia may also be found in dermatofibroma, and their presence may explain the dermoscopic aspect of ridges and furrows.11 Hügel H. Fibrohistiocytic skin tumors. J Dtsch Dermatol Ges. 2006;4:544-55.,44 Zaballos P, Puig S, Llambrich A, Malvehy J. Dermoscopy of dermatofibromas: a prospective morphological study of 412 cases. Arch Dermatol. 2008;144:75-83. This association between dermoscopic and pathologic findings is corroborated by the case herein described. Although dermoscopy is an important tool in the diagnosis of melanocytic and non-melanocytic skin lesions, the histopathologic examination is important when there is disagreement between clinical and dermoscopic diagnosis.

  • Financial Support: None.
  • *
    Work carried out at the Universidade de Pernambuco (UPE) - Recife (PE), Brazil.

REFERENCES

  • 1
    Hügel H. Fibrohistiocytic skin tumors. J Dtsch Dermatol Ges. 2006;4:544-55.
  • 2
    Kilinc Karaarslan I, Gencoglan G, Akalin T, Ozdemir F. Different dermoscopic faces of dermatofibromas. J Am Acad Dermatol. 2007;57:401-6.
  • 3
    Lin J, Han S, Cui L, Song Z, Gao M, Yang G, et al. Evaluation of dermoscopic algorithm for seborrhoeic keratosis: a prospective study in 412 patients. J Eur Acad Dermatol Venereol. 2014;28:957-62.
  • 4
    Zaballos P, Puig S, Llambrich A, Malvehy J. Dermoscopy of dermatofibromas: a prospective morphological study of 412 cases. Arch Dermatol. 2008;144:75-83.

Publication Dates

  • Publication in this collection
    May-Jun 2016

History

  • Received
    14 Sept 2014
  • Accepted
    25 Nov 2014
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