Cellular angiofibroma: analysis of 25 cases emphasizing its relationship to spindle cell lipoma and mammary-type myofibroblastoma

Abstract

Cellular angiofibroma represents a rare benign mesenchymal tumor, occurring mainly in the superficial soft tissue of the genital region. The involvement of 13q14 in some cases confirmed the morphological suggested link with spindle cell lipoma and mammary-type myofibroblastoma. We analyzed the clinicopathological and immunohistochemical features of 25 cases, and performed in a number of cases additional molecular studies. There were 17 female and 8 male patients (age ranged from 27 to 83 years); females tended to be younger. A marked predilection for the vulva (n=13) was observed, and neoplasms in males were predominantly located in the inguinal region (n=4), and one case each in the scrotum, perianal, the knee, and the upper eyelid. The tumors arose most commonly in the superficial soft tissue and were well circumscribed in all but two cases. The tumor size ranged from 1 to 9 cm. All lesions were composed of spindle-shaped cells associated with numerous small- to medium-sized blood vessels; however, a broad morphological variation with foci of lipogenic differentiation in nine cases and sarcomatous transformation in one case was found. By immunohistochemistry, 11 out of 22 cases expressed CD34. A focal reaction for α-smooth muscle actin was observed in 9 out of 22 cases, and two cases each stained weak and focally positive for epithelial membrane antigen and CD99. In all seven cases tested, a monoallelic deletion of RB1 was detected by FISH analysis. Follow-up, available in 14 patients, showed neither local recurrence nor metastasis. In conclusion, we affirm the link between cellular angiofibroma, spindle cell lipoma, and mammary-type myofibroblastoma, showing a spectrum of one entity with morphological variations dependent on anatomic location.