Angiomyofibroblastoma-like tumor (lipomatous variant) of the inguinal region of a male patient.

A case of angiomyofibroblastoma-like tumor (lipomatous variant) that arose in the subcutis of the inguinal region of a 45-year-old man is presented. The maximum dimension of the tumor measured 39 mm and it was well circumscribed. Histopathological examination revealed a close admixture of plump spindle or stellate cells and mature adipocytes. These were arranged haphazardly or formed interconnecting thin cellular trabeculae on the myxoid or edematous background. The tumor was highly vascularized and contained a moderate amount of collagen fibers. Immunohistochemically, the tumor cells were positive for vimentin, CD34 and the estrogen receptor, but negative for alpha-smooth muscle actin and desmin. The differential diagnosis between the lipomatous variant of angiomyofibroblastoma and cellular angiofibroma or spindle cell lipoma is discussed, and the pathogenetic hypotheses about the occurrence of mature adipocytes within benign fibroblastic or myofibroblastic neoplasms are mentioned briefly. It is important for surgical pathologists to be acquainted with the occasional presence of adipocytes in these neoplasms to avoid misinterpretation.