Abstract: We report the 18F-FDG PET/CT appearance of a metastatic biopsy-proven malignant fibroxanthoma of the ankle. A 41-year-old female patient with a history of scleroderma presented with a fungating mass in the left ankle. Shave biopsy of the overlying skin showed atypical fibroxanthoma (AFX). Staging FDG PET/CT demonstrated a hypermetabolic exophytic soft tissue mass in the left ankle with local extension to bone and widespread metastatic disease including pulmonary parenchyma, nodes, bone marrow, and skeletal muscle. While rare, knowledge of the potential aggressive nature of AFX is important for accurate diagnosis.