Lipomatous variant of angiomyofibroblastoma: report of two cases and review of the literature.

Angiomyofibroblastoma (AMF) is a rare, benign, mesenchymal tumor occurring mainly in the female genital tract. Some cases contain scattered mature adipocytes, but the lipomatous variant in which mature adipose tissue is prominent or striking is rare. Only five cases have been reported in the English literature. We report two more such cases that were composed of 70 to 80% and 30 to 40% adipose tissue, respectively. Immunohistochemical analysis showed that the tumor cells were positive for estrogen receptor, progesterone receptor, vimentin, and Bcl-2, and negative for cytokeratin AE1/1, EMA, and CD117. Tumor cells in the first case were positive for CD34 but not desmin and muscle-specific actin. The opposite expression profile of these three markers was observed in tumor cells in the second case: positive for desmin and muscle-specific actin and negative for CD34. Rare cells were positive for S-100 in adipose-rich areas in the first case. Our findings indicate that the tumor cells in the lipomatous variant have similar immunoprofile to those of usual AMF and support the concept that the lipomatous variant probably represents an extreme end of a wide spectrum of differentiation in AMF.