Clinical aspects of the rhabdoid tumor of the kidney: a report of the National Wilms' Tumor Study Group.

Rhabdoid tumor of the kidney (RTK), originally described as a monophasic sarcomatous variant of Wilms' tumor, is now recognized as a highly malignant, non-Wilms' tumor possibly of neuroectodermal origin. Twenty-one National Wilms' Tumor Study patients with this tumor were treated in the years 1969 through 1978. Mean patient age was 18 months with 16 of the 21 younger than 2 years at diagnosis. Two patients were Stage 1, 10 Stage II, 5 Stage III, and 4 Stage IV. One patient only is continuously disease free and another is surviving disease free following excision of bilateral pulmonary metastases. One patient died of sepsis early during therapy. Thus 18 of the 19 patients who relapsed died, 15 within 1 year of diagnosis, all with progressive tumor growth. The rapid appearance of metastases (mean 4 months), often to multiple sites, and short subsequent survival signal a very malignant tumor resistant to current treatment stratagems.