Soft-tissue extrarenal rhabdoid tumor with a unique long-term survival.

Rhabdoid tumors of kidney and extrarenal rhabdoid tumors are identified by a round-epithelioid cell morphology and a bland immunophenotype, but a distinctive ultrastructure dominated by paranuclear whorls of intermediate filaments, most usually of vimentin. These tumors are also known to be highly aggressive malignancies, which, typically, bear a poor prognosis, frequently measured in months following initial presentation. The authors record the case a soft-tissue rhabdoid tumor in a 12-year-old boy with a unique long-term survival in excess of 16 years. The features of this case are documented, with a brief summary of histological, immunohistochemical, ultrastructural, and genetic characteristics of this entity.