Angiomyofibroblastoma of the female genital tract: analysis of 17 cases including a lipomatous variant

The clinicopathological and immunohistochemical profile of 17 cases of angiomyofibroblastoma (AMF) arising in the genital tract of females is reported. The lesions usually presented as painless masses and were located in the superficial vulvar region (15 cases), canal of Nuck (one case), and perineum (one case) in women ranging in age from 38 to 60 years (median, 46 years). The tumors were well delineated and ranged in size from 2 to 8 cm in greatest dimension. Microscopically, they were composed of spindled and epithelioid mesenchymal cells arranged in cords and nests preferentially arrayed around numerous small to medium-sized vessels. Mitotic activity ranged from 0 to 7 mitoses per 50 high-power fields (HPF) with no abnormal mitotic figures. Minimal nuclear atypia was appreciated. Intralesional fat was present in 12 cases and in two of these cases constituted most of the tumor (lipomatous variant of AMF). Tumor cells expressed vimentin (five of five cases), estrogen receptor protein (six of six cases), progesterone receptor protein (five of six cases), desmin (six of eight cases), CD34 (one of six cases), and smooth muscle actin (one of seven cases). None of the eight women with follow-up of up to 25 years (mean, 7.8 years) after simple excision developed a recurrence. This study confirms the benign nature of AMF, broadens its morphological spectrum to include a lipomatous variant, and proposes an origin from a perivascular stem cell that is capable of myofibroblastic and fatty differentiation.