Atrophic dermatofibroma: a case report and review of the literature.

BACKGROUND Atrophic dermatofibroma is an uncommon variant of dermatofibroma. It lacks the classic clinical features of a dermatofibroma and is often misdiagnosed. OBJECTIVE To describe the clinical and histologic features of atrophic dermatofibroma. METHODS Case report and review of the literature. RESULTS A 45-year-old white woman was found to have a 7 mm x 5 mm atrophic, depressed lesion in the right axilla. A clinical diagnosis of anetoderma was made and the lesion was excised with minimal margins. Histopathologic examination revealed findings consistent with dermatofibroma. However, focal CD34 staining and involvement of superficial subcutaneous tissue raised concern regarding an early dermatofibrosarcoma protuberans developing in a dermatofibroma. The patient underwent Mohs micrographic surgery (MMS) for definitive treatment. The final diagnosis is thought to be atrophic dermatofibroma. Reported cases in the English language literature are reviewed and the clinical and histopathologic findings are described. CONCLUSION Atrophic dermatofibroma is a well-described, yet uncommon, variant of dermatofibroma. It is often clinically misdiagnosed, and histopathologic evaluation can be misleading. The clinician and pathologist should consider this diagnosis in the evaluation of atrophic, depressed lesions.