An isolated ulcerated forehead lesion in a 70-year-old man

Abstract

A 70-year-old man presented with an 8-week history of an isolated painless forehead lesion, which had been gradually enlarging. He had a history of Crohn disease, which had been controlled for over 10 years with azathioprine. Physical examination revealed a solitary plaque 20 9 19 mm) on the mid-forehead with a nontender pink fleshy base and prominent central ulceration, in the absence of palpable lymphadenopathy (Fig. 1a). Histopathological findingsA diagnostic biopsy demonstrated infiltration of the dermis and subcutaneous tissue by a large, pleomorphic lymphocyte population with no obvious epidermotropism. Immunophenotyping showed the large atypical cells to be positive for CD20, CD30, and MUM-1, and negative for CD3, CD5, CD10, cyclin-D1 and ALK-1. In situ hybridization (ISH) for Epstein-Barr virus (EBV) was strongly positive within the large cells. Many reactive T cells were present. A staging computed tomography scan was normal, as were full blood count, lactate dehydrogenase and biochemistry profile. Plasma EBV PCR was positive. Azathioprine was discontinued, resulting in complete resolution of this lesion within a month (Fig. 1b).What is your diagnosis?