CLEAR-CELL SARCOMA WITH MELANIN PIGMENT - POSSIBLE SOFT-TISSUE VARIANT OF MALIGNANT-MELANOMA - CASE-REPORT

The clear-cell sarcoma of tendons and aponeuroses is now a well recognized type of soft-tissue sarcoma with distinct morphological features but until recently its origin was uncertain. The long but protracted clinical course of these tumors, with multiple recurrences and eventual metastases as observed originally by Enzinger is thus amply confirmed by these subsequent case reports. Our patient, with a history of a gradually progressing nodule in the left thumb for a period of 3 years until a ray amputation of the thumb was done, had a similar predictable course, with a recurrent or metastatic disease at 1.5 years following amputation. The tumor, which on light microscopy showed the characteristic features of a demonstrable sarcoma of tendons and aponeuroses, had dimonstrable melanin-pigment granules in the tumor cells. On electron microscopy, melanosomes and premelanosomes were demonstrated, as recently observed by Bearman and associates, Hoffman and Carter, and McKenzie. Melanosomes are highly specific cytoplasmic organelles which are seen in various tumors of neural-crest origin, including melanomas, melanotic progonomas, and peripheral nerve tumors. The presence of these organelles within clear-cell sarcomas strongly suggests a neural-crest origin for these tumors.