Clear Cell Sarcoma
Definition
- Primary soft tissue neoplasm exhibiting evidence of melanocytic differentiation
Alternate / historical names
- Malignant melanoma of soft parts
- Clear cell sarcoma of tendons and aponeuroses
Diagnostic criteria
- Irregular nests of cells separated by fibrous septa
- Cells may be in short fascicles, whorls or solid sheets
- Necrosis frequent
- Rarely with prominent lymphocytes along septa creating a seminoma-like pattern
- Rarely with discohesion creating an alveolar pattern
- Round to fusiform, non-pleomorphic cells
- Pleomorphism rare except in recurrent disease
- Regular vesicular nuclei
- Prominent single nucleolus
- Multinucleated tumor giant cells may be seen
- Mitotic figures infrequent
- Median 2/10 HPF, rarely up to 43/10 HPF
- Moderate to abundant cytoplasm
- Clear to granular eosinophilic
- Glycogen frequently present
- Rhabdoid cells may be seen in occasional cases
- S100 and HMB45 positive in about 80% of cases
- Melanin stain frequently positive
Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting: July 19, 2007
Last Update: June 26, 2008
