Angiomyofibroblastoma of the vulva: a large pedunculated mass formation.

Angiomyofibroblastoma is a rare, usually small benign mesenchymal tumor that occurs in vulvar lesions of premenopausal women. A case of angiomyofibroblastoma that arose as a unique pedunculated and particularly large mass in the left vulva of a 48-year-old woman is presented herein. The patient had been aware of a gradually enlarged mass of 7 years duration without any other gynecological symptoms or signs. The maximum dimension of the tumor measured 11 cm. The resected tumor was well circumscribed with a bulging and glistening cut surface. Histological examination revealed an admixture of irregularly distributed hypercellular and hypocellular areas with spindled, plump spindled, or plasmacytoid stromal cells and abundant venular or capillary-sized vessels. Stromal cells characteristically cluster around delicate vessels within an edematous to collagenous matrix. In the present case, intralesional adipose tissue was present throughout the tumor. There was no significant nuclear atypia, and mitotic figures were very sparse. There was little stromal mucin throughout the tumor. Immunohistochemically, the stromal cells were characterized by strong reactivity for vimentin and CD34, with focal reactivity for desmin and alpha smooth muscle actin. Both estrogen and progesterone receptors were diffusely expressed in the stromal cells. These histological findings are consistent with angiomyofibroblastoma and support the hypothesis that angiomyofibroblastoma originates from perivascular stem cells with a capacity for myofibroblastic and fatty differentiation.