Cellular Angiofibroma With Sarcomatous Transformation: Case Report With Molecular Characterization and Review of the Literature.

Cellular angiofibroma is a benign mesenchymal neoplasm which usually occurs in the vulvovaginal or inguinoscrotal areas. Although benign, cellular angiofibroma may rarely undergo sarcomatous transformation. We report a case of vulvar cellular angiofibroma with sarcomatous transformation in a 62-yr-old woman and a literature review of previously reported cases. By immunohistochemistry, our case was positive for vimentin and ER, mostly negative for smooth muscle markers, and showed patchy reactivity for CD10, Pan-TRK, and Rb1. The bland component was negative for p16 with wild-type p53 expression, while the sarcomatous area showed strong, diffuse p16 staining with p53 overexpression. Targeted DNA and RNA next-generation sequencing of the bland area showed chromosome 9p/9q copy number loss, while the sarcomatous area showed TP53 (p.G154V) mutation (90% allele frequency) and copy number loss of chromosome 17p (including TP53). Whole transcriptome sequencing was negative for tumor-associated gene fusions. As the lesion was completely encapsulated and excised, and with limited published data indicating an uneventful clinical course, the decision was made to follow the patient with no further therapeutic intervention. Four months following excision, the patient has no signs or symptoms of local recurrence.