Atypical polypoid dermatofibroma: report of two cases.

Two cases of a hitherto undescribed special variant of dermatofibroma are reported. A man and a woman, aged 57 and 52 years, respectively, had slowly growing cutaneous tumors on the lower extremities. The tumors were exophytic and polypoid, 10 and 6 cm in maximal diameters, respectively; they were covered by rough nonulcerated skin and were joined by a short pedicle to an indurated base. Histologic examination showed some features of an otherwise conventional dermatofibroma, whereas the polypoid component was hypercellular and showed striking atypia and scattered mitotic figures. After 32 and 28 months' follow-up, the lesions did not recur after surgical excision. We suggest the term atypical polypoid dermatofibroma to summarize the special clinicopathologic features of these tumors.