A 63-year-old man presented with a palpable inguinal mass. Radiologic exam demonstrated that the mass extended into the scrotum but was not attached to (or included in) the spermatic cord. The mass was easily excised and measured 9.5 x 5.8 x 2.2 cm with a solid, tan-colored cut surface.

Pathologic Findings This is well-circumscribed neoplasm surrounded by a thin layer of fibroadipose tissue. The lesion consists of spindle cells with short stubby or more tapering nuclei and indistinct cytoplasm, in areas showing delicate cytoplasmic processes. These cells are distributed in a collagenous stroma which contains numerous rounded blood vessels, many having thickened walls. Scattered between the spindle cells, there are readily identified mast cells as well as focally prominent plasma cells and lymphocytes. There is no atypia or pleomorphism. There are just rare admixed mature adipocytes. Immunohistochemical stains show that the tumour cells in this case are entirely negative for CD34, desmin and S-100 protein. However, importantly, they are also negative for Rb, indicating that the product of this gene on the long arm of chromosome 13 is lost/deleted.

CELLULAR ANGIOFIBROMA