Fig. 3

Atypical dermatofibroma. a Similar to other dermatofibroma variants, the tumor is relatively circumscribed and shows overlying epidermal hyperplasia. b The tumor shows a variably fascicular-to-storiform growth pattern. c Entrapment of hyaline dermal collagen is a helpful diagnostic clue. d The degree of nuclear atypia and pleomorphism can be striking. Without careful attention to the other histologic features, there is significant risk for misdiagnosis as sarcoma