Embryonal rhabdomyosarcoma of breast, pleura, and retroperitoneum diagnosed from pleural fluid cytology.

Embryonal rhabdomyosarcoma (ERMS) is a malignant small blue round cell tumor which is commonly seen in head and neck region. Breast and pleural involvement are uncommon. Rhabdomyosarcoma has been rarely reported in the body fluids like ascitic, pleural, and cerebrospinal fluid. In this article, we report an interesting case of ERMS which had deceptive small blue round cells in pleural fluid. The cytomorphological features along with a panel of immunocytochemical markers helped in arriving at the definite diagnosis. Later, biopsy from the breast lump and retroperitoneal mass also revealed the same tumor. This case is reported since it is rare to find sarcoma cells in pleural fluid and highlight the diagnostic difficulties faced during interpretation.