Clear Cell Sarcoma : Differential Diagnosis
In poorly-fixed or suboptimally processed specimens, the tumor cells may appear more compact and hyperchromatic with dense eosinophilic cytoplasm. The appearance may resemble small cell carcinoma or high-grade sarcomas (e.g. alveolar rhabdomyosarcoma). Other entities in the differential diagnosis include fibrosarcoma, malignant peripheral nerve sheath tumor, cellular blue nevus, and nodular malignant melanoma. Features favoring clear cell sarcoma (CSS) include deep location, sparing of overlying skin and dermis, uniform bland spindle cells with clear cytoplasm, and the presence of chromosomal translocation t(12;22)(q13;q12). Conventional melanomas donít carry this translocation but instead show BRAF mutations which are absent in CSS. Cellular blue nevi are dermal-based lesions and lack prominent nucleoli.