Atypical fibroxanthoma--a retrospective immunohistochemical study of 42 cases.

PURPOSE: Atypical fibroxanthoma is a cutaneous dermal malignancy that presents on the sun-damaged skin of elderly people. It requires a definitive diagnosis, from a high-grade sarcoma to a nonmesenchymal neoplasm. The recommended treatment protocol differs from similar histologically related tumors; thus, a diagnosis of atypical fibroxanthoma should fulfill strict histologic and immunohistochemical stain criteria. The use of these standards will exclude other skin malignancies, including malignant fibrous histiocytoma, angiosarcoma, malignant melanoma, and squamous cell carcinoma. This study was performed with the aim of identifying key immunostains to develop diagnostic criteria.

MATERIALS AND METHODS: Forty-two cases were studied retrospectively over a 10-year period using a panel of immunostains.

RESULTS: The average age at presentation was 78 years, with a male predominance. The scalp was found to be the most common site of occurrence, although other investigators have found the forehead, cheeks, nose, and ears as the prevailing sites of presentation.

CONCLUSIONS: An extensive panel of immunohistochemical stains can be used to prove a diagnosis of atypical fibroxanthoma.