Clear cell sarcoma of tendons and aponeuroses: malignant melanoma of soft tissues? Report of four cases.

In a survey of 246 soft tissue sarcomas in the extremities and limb girdles reported to the Finnish Cancer Registry in 1960-1969, two clear cell sarcomas of tendons and aponeurones were diagnosed. We subsequently diagnosed two more examples. Three tumors were located in the foot and one in the wrist. The histology of the tumors was characteristic, and three of them were shown to contain brown pigment tinctorially indistinguishable from melanin. The pigment could be bleached with potassium permanganate. Ultrastructural studies performed in the most recent case revealed premelanosomes in the cytoplasm of tumor cells. Increasing evidence in the literature and results of the present study seem to suggest that clear cell sarcoma of tendons and aponeuroses represents a soft tissue malignant melanoma.