Atypical Fibroxanthoma of the Skin

Abstract

Atypical fibroxanthomas are rare cutaneous neoplasms classified among fibrohistiocytic tumors. They most commonly develop in elderly individuals with a history of chronic sun damage and are typically located on the head, shoulders, and upper back. Atypical fibroxanthoma is frequently associated with other skin tumors and is characterized by locally destructive growth with extremely rare metastases (1%–2% of cases). However, in immunosuppressed patients, the tumor may demonstrate more aggressive behavior. The clinical presentation of atypical fibroxanthoma is nonspecific. It appears as a pink or reddish-pink nodule or papule. Atypical fibroxanthoma lacks specific dermatoscopic features; common findings include polymorphous vessels (linear, dotted, glomerular, arborizing) and chrysalis structures, which are not sufficient to reliably differentiate it from clinically similar lesions. Its resemblance to aggressive neoplasms such as amelanotic melanoma and Merkel cell carcinoma presents a diagnostic challenge. A definitive diagnosis relies on characteristic histopathologic and immunohistochemical findings. The gold standard of treatment is wide local excision. Mohs micrographic surgery may be considered. Other treatment modalities are not recommended because of the high recurrence rate. We report a case of atypical fibroxanthoma in a 72-year-old male with photodamaged skin and a history of other skin tumors (basal cell carcinomas self-treated with liquid nitrogen cryotherapy). Histopathologic examination revealed an ulcerated, polymorphic, poorly differentiated tumor with marked anaplasia and areas of epithelioid and spindle-cell morphology. The differential diagnosis included melanoma, fibrosarcoma, and atypical fibroxanthoma. The patient underwent wide excision of the tumor, with the specimen submitted for histologic and immunohistochemical analysis. The postoperative period was uneventful with scar formation, and no recurrence was observed during follow-up.