Pathology of Clear Cell Sarcoma of Tendons and Aponeuroses
(Malignant Melanoma of Soft Parts)
Clear cell sarcoma
of tendons and aponeuroses is a rare
aggressive, soft tissue
initially named malignant
melanoma of soft parts.
It was originally described by Enzinger et al in 1965.
The tumour was called malignant melanoma of soft parts because it shows melanocytic differentiation.
Clear cell sarcoma stain positive for the melanocyte immunohistochemical markers HMB-45 and S-100. It is thought to derive from neural crest cells. These markers are useful for distinguishing clear cell sarcoma from epithelial tumours and synovial sarcomas.
It is a slow growing, progressive tumour with poor prognosis.
The patients are mostly young adults
between the ages of 20 and
40 years with a higher incidence in female.
Poor prognosis is
indicated by large size of the tumour , presence of necrosis and
Tumors <5 cm are much less
likely to recur or metastasize, whereas those >5 cm are more commonly
associated with metastatic disease.Focal
or diffuse tumor necrosis also correlates with a worse prognosis,
independent of tumor size
The EWS/ATF1 fusion transcript is detectable in almost 90% of cases.
Differential diagnosis of clear cell sarcoma:
1. Malignant melanoma (mitotic activity, cellular atypia and nuclear
pleomorphism more prominent in melanoma) ;
It has been
suggested that CD117 immunoreactivity, which was positive in metastatic
melanoma, but not in clear cell sarcoma, may be useful for differentiation
of these tumours.
Clear cell sarcoma of the temporal region: case
report, review of the literature, and genetic analysis.
J Oral Maxillofac Surg. 2009;67:910–4.
6. Synovial Sarcoma (monophasic type),
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