Mycosis fungoides exhibiting features of a dermatofibroma: a case report and review of the literature.

We present the case of a 60-year-old male with known stage IA mycosis fungoides (MF) who developed a suspicious tumor within a pre-existing lymphomatous plaque of the right forearm. Microscopy revealed an unusual mixed fibrohistiocytic proliferation as well as atypical intraepidermal and dermal lymphocytes. There was no evidence of large-cell transformation. Histopathological, immunohistochemical and clinical clues suggest this lesion might not have represented a dermatofibroma, but rather a hitherto unreported dermatofibroma-like process arising within a lesion of MF. The potential impact of this atypical lesion on the prognosis and clinical management of this patient highlights the importance of recognizing unusual clinical presentations of more common, benign lesions within this patient population.