Cellular angiofibroma: a benign neoplasm distinct from angiomyofibroblastoma and spindle cell lipoma.

Four cases of a distinctive soft-tissue tumor of the vulva are described. They were characterized by occurrence in middle-aged women (39-50 years), small size (< 3 cm), and a usually well-circumscribed margin. The preoperative clinical diagnosis was that of a labial or Bartholin gland cyst in three of the four cases. The microscopic appearance was remarkably consistent and was characterized by a cellular neoplasm composed of uniform, bland, spindled stromal cells, numerous thick-walled and often hyalinized vessels, and a scarce component of mature adipocytes. Mitotic activity was brisk in three cases (up to 11 mitoses per 10 high power fields). The stromal cells were positive for vimentin and negative for CD34, S-100 protein, actin, desmin, and epithelial membrane antigen, suggesting fibroblastic differentiation. Two patients with follow-up showed no evidence of recurrence. The differential diagnosis of this distinctive tumor includes aggressive angiomyxoma, angiomyofibroblastoma, spindle cell lipoma, solitary fibrous tumor, perineurioma, and leiomyoma. The designation of "cellular angiofibroma" is chosen to emphasize the two principal components of this tumor: the cellular spindle cell component and the prominent blood vessels.