[A rare low-grade malignant scalp tumor. Atypical fibroxanthoma]

A 79-year-old patient presented with an asymptomatic scalp tumor which had grown over the past 9 months. Based on clinical, histological and immunohistochemical staining, we made the diagnosis of an atypical fibroxanthoma (AFX). AFX is a rare tumor, but important in the differential diagnosis of other scalp tumors. The routine histological staining allows one to identify a malignant fibrous histiocytoma, while a spindle-cell malignant melanoma can be excluded with immunohistochemical staining. An anaplastic squamous cell carcinoma cannot always be separated with completed certainty from atypical fibroxanthoma. AFX is a low-grade malignant tumor and most cases behave in a benign fashion. After complete excision, we recommend follow-up for a number of years because of the possibility of local recurrence.