Atypical fibroxanthoma, rare and often unrecognized cutaneous soft tissue tumor - a case report and review of the literature

Atypical fibroxanthoma (AFX) is a rare cutaneous soft tissue tumor typically occurring in the elderly on sun exposed skin. Histologically, it is composed of pleomorphic, atypical cells with multiple mitoses including atypical mitotic figures resembling undifferentiated malignant tumor. AFX is considered to be a benign tumor with almost uniformly excellent prognosis following conservative therapy if strict diagnostic criteria are applied. We present a case report of 68-year-old man with a skin tumor in the temporo-parietal region. Histomorphological and immunohistochemical analysis led us to the diagnosis of atypical fibroxanthoma. We offer a review of terminology and categorization of this tumor and an overview of immunohistochemical markers useful in differential-diagnostic process to rule out other malignant tumors, because AFX is a diagnosis of exclusion. The correct diagnosis prevents unnecessary overtreatment of the patient.