Rhabdomyosarcoma with rhabdoid-like features.

We describe an unusual case of a rhabdomyosarcoma (RMS) in that it had rhabdoid-like cells histologically and occurred in a female who had undergone bone marrow transplantation for chronic myelogenous leukemia. The tumor was composed of loosely cohesive cells with abundant eosinophilic cytoplasm and exhibited PAS-negative paranuclear inclusions. The tumor cells had positive vimentin, muscle-specific actin, sarcomeric actin and desmin immunoreactivity. Ultrastructurally, the tumor cells contained aggregates of thin and thick filaments. In situ hybridization did not detect human papillomavirus or cytomegalovirus DNA, or EBV DNA or RNA. The tumor fulfilled the current criteria for a diagnosis of RMS; however, it could not be further classified. The tumor appears to have a good prognosis as there has been no evidence of recurrence five years after resection. As this is the first case report, to our knowledge, of this type of tumor following bone marrow transplant, the significance of this association is not yet clear.