Vulvar Cellular Angiofibroma With Cytologic Atypia and Sarcomatous Transformation: A Clinicopathologic Analysis.

Cellular angiofibromas (CAFs) are benign mesenchymal neoplasms of the vulva and lower genitourinary tract. Although most cases are benign with excellent prognosis, data on CAFs with cytologic atypia (aCAF) and sarcomatous transformation (tCAF) is limited. We identified 13 vulvar CAFs comprising 4 aCAFs and 9 tCAFs. The median age at presentation was 49  yr (40-84). All tumors involved the subcutis with a median size of 4.75 cm (0.8-11.7). Vascular and stromal hyalinization was present in all cases. Fascicular growth pattern and chronic perivascular inflammation were seen in 10 cases, followed by wispy collagen in 11 and stromal inflammation in 12. Common features were fat entrapment (n=8), stromal edema (n=7), and hemangiopericytoma-like vessels (n=5), while myxoid change, necrosis (n=3 each), hemorrhage, collagen bundles (n=2 each), solitary fibrous tumor-like appearance, and large hyalinized vessels (n=1 each) were rare. The atypia ranged from isolated atypical cells to foci of multinucleated cells, with brisk mitoses in 1 case. The sarcomatous transformation involved 10% to 80% of total tumor volume and comprised features of well-differentiated liposarcoma, pleomorphic liposarcoma, leiomyosarcoma, and spindle and epithelioid cell sarcoma. Diffuse p16 expression was present in 2 tCAFs. Of 10 patients with available follow-up (median: 103.3 mo, 13.3-156.6), 2 (20%) recurred at 41 mo and 66 mo and remained disease-free at 157 and 99  mo post reexcision, respectively. The study provides a detailed clinicopathologic characterization of rare variants of CAF, aCAFs, and tCAFs, and reports rare recurrences, most likely due to incomplete surgical excision.