5th June 2025

A 76-year-old woman is referred to you with a lesion on her right lower leg.

A 76-year-old woman is referred to you with a lesion on her right lower leg. It has been present for about 3 months and increased rapidly in size over this time period. On examination there is a firm nodule with a bluish-red colour. There is no evidence of extracutaneous spread. A biopsy is performed which shows proliferation of centroblasts and immunoblasts within the dermis, forming a sheet pattern. Immunohistochemistry is MUM1 and Bcl-2 positive. What is the most likely diagnosis?

Select the SINGLE most appropriate option from the list below. Select ONE option only.