MR appearance of clear cell sarcoma of tendons and aponeuroses (malignant melanoma of soft parts): radiologic-pathologic correlation.

Clear cell sarcoma of tendons and aponeuroses (CCSTA) is a rare aggressive soft tissue tumor that frequently produces melanin. Its MR findings are rarely described in the literature. We report the case of a previously healthy 54-year-old man with clear cell sarcoma of the thigh who presented with a large painless mass of 1 year's duration. MR imaging showed the tumor to be of high signal intensity on fast spin-echo and STIR images. Both fine needle aspiration and excisional biopsy showed abundant melanin pigments. Histologic diagnosis was compatible with CCSTA.