Clear cell sarcoma of tendons and aponeuroses: a comparative study of 13 cases with a provisional subgrouping into the melanotic and synovial types.

Electron microscopy of two cases of clear cell sarcoma of tendons and aponeuroses showed different fine structures. On the basis of these differences a proposed division is made of melanotic and synovial types of the tumor. A subsequent comparative histological study carried out on these tumors showed that there were histological criteria to separate the melanotic and synovial types of sarcoma. Using these histological criteria eleven further cases of clear cell sarcoma in the files of the Tumor Registry were subdivided. Review of the Tumor Registry material showed that eight were melanotic type tumors and one was a further synovial type tumor. Using these histological criteria there are two further cases in the Tumor Registry which are not clearly classifiable into either group. The present observations indicate that the majority of the so-called clear cell sarcomas are in reality "melanomas of soft parts" with a minority of this type of tumor being of "synovial type".