Cytological Features of Clear Cell Sarcoma in Exfoliative and Effusion Cytology Specimen-A Case Report and Literature Review.

Clear cell sarcoma of soft tissue (CCSST) with malignant effusion is a rare yet clinically aggressive appearance, which may pose a diagnostic pitfall with its overlapping cytomorphologic features with metastatic melanoma and carcinoma. In this article, we reported a case with metastatic clear cell sarcoma of soft tissue with positive cytological findings in the sputum, as well as the peritoneal fluid and pericardial fluid. The cytological findings were compared and contrasted with cases reported in the literature. Malignant effusion cytology, variable positivity of melanocytic immunocytochemistry markers (namely S100, SOX10, Melan-A, HMB-45) and confirmatory molecular pathology techniques (e.g., detection of underlying EWSR1 gene rearrangement by fluorescent in situ hybridization or by reverse transcription polymerase chain reaction for EWSR1-ATF1 gene fusion) formed the key diagnostic approach of this entity.