Malignant rhabdoid tumor of the brain and kidney in a child: clinical and pathologic features.

Malignant rhabdoid tumor (MRT) is most frequently found in the kidney, but can occur in other tissues including the brain. The simultaneous appearance of MRT in the brain and kidney has rarely been described. We report the first fully described case of simultaneous appearance of MRT in the kidney and cerebellum of an 8-month-old boy. Cytoplasmic inclusion-like masses, representing aggregates of intermediate filaments, positively stained by Vimentin and by epithelial membrane antigen, were abundant in the kidney tumor but rare in the cerebellar tumor, suggesting that this often-described characteristic of kidney MRT can be an infrequently observed feature of brain MRT, which consequently may be thought to represent another type of tumor.