Atypical fibroxanthoma (AFX) is a dermal spindle-cell sarcoma that is considered a superficial and clinically benign presentation of pleomorphic dermal sarcoma, malignant fibrous histiocytoma, and undifferentiated pleomorphic sarcoma. AFX appears clinically as a discrete red or pink nodule or papule, most commonly on the head and neck region of sun-damaged elderly patients. Histologic findings on routine hematoxylin and eosin staining reveal spindle-shaped, large, and pleomorphic tumor cells throughout the dermis. Immunohistochemistry is not specific for AFX, and the diagnosis is generally one of exclusion. AFX is best treated by complete surgical excision, with Mohs micrographic surgery considered the treatment of choice. Metastasis rarely occurs, but there is a high rate of local recurrence, especially in patients who are immunosuppressed.

Atypical fibroxanthoma (AFX) is a dermal spindle-cell sarcoma that is considered a superficial and clinically benign presentation of pleomorphic dermal sarcoma, malignant fibrous histiocytoma, and undifferentiated pleomorphic sarcoma.