Clear cell atypical fibroxanthoma arising from vaginal stump: A case report from unusual location with a history of radiation therapy

Clear cell atypical fibroxanthoma (CCAFX) is a rare variant of superficial undifferentiated pleomorphic sarcoma, and considered as a tumor of intermediate malignant potential with a relatively indolent clinical behavior. The patient was a 70-year-old female, with a history of a surgery and radiation therapy for rectal adenocarcinoma 10 years ago, who underwent incomplete excision for an exophytic mass on the vaginal stump. Histologically, the tumor was composed of polygonal cells with clear vacuolated cytoplasm and enlarged, vesicular nuclei with prominent nucleoli. The tumor cells were immunopositive for CD10, CD68, CD99, vimentin and procollagen-1, but negative for pan-cytokeratin, HMB45, Melan-A, S100 protein, CD117 and smooth muscle actin. Based on histomorphologic, immunohistochemical, and ultrastructural findings, a diagnosis of CCAFX with histocytic and fibroblastic differentiation was rendered. The tumor recurred during the follow-up period of 4 months. Recognition of CCAFX in the unusual location is important for the proper diagnosis and optimal management.