Angiomyofibroblastoma of the vulva: a mitotically active variant?

A case of angiomyofibroblastoma in a 48-year-old woman is reported. The tumor occurred as a left vulval mass and was treated by simple excision. It was located in the subcutaneous tissue of the left vulva and was well circumscribed, measuring 2.8 x 2.7 x 2.5 cm. Microscopically, the tumor was composed of hypocellular and cellular areas with well-developed small vessels. Spindle or polygonal cells were arranged with perivascular accentuation in an edematous or fibrocollagenous background. Some spindle-shaped or polygonal stromal cells were also arranged in epithelioid nests. In some areas, mitoses were frequent (maximum 3/10 high-power field). Immunohistochemically, the stromal cells were positive for vimentin and desmin, but negative for alpha-smooth muscle actin, S-100, neurofilament, estrogen receptor, progesterone receptor, CD31 and CD34. The average labeling index of Ki-67 in stromal cells was 3.1%. Ultrastructural analysis demonstrated that the stromal cells adhered with primitive junctions and contained intermediate filaments with no focal density in the cytoplasm. These findings were consistent with angiomyofibroblastoma, although previously reported cases did not show so many mitoses. Therefore, this case was suggested to be a mitotically active variant.