Cystic partially differentiated nephroblastoma and multilocular cyst of the kidney. Report of two cases of so-called multilocular cyst of the kidney.

Two cases of so-called multilocular cyst of the kidney are presented. Although both cases satisfied all of the criteria which characterize the multilocular cyst of the kidney, one had cystic lesions and neoplastic lesions (nephroblastoma-like lesions) and the other had only cystic lesions and was complicated with hamartoma. We prefer the term "cystic partially differentiated nephroblastoma" as the diagnostic term for the former and "multilocular cyst of the kidney" for the latter. A study of 40 reported cases of multilocular cystic lesions of the kidney revealed that cases having only cystic lesions were distributed in all ages from 4.5 months to 71 years and that cases having neoplastic lesions were seen in infants from 4 months to 2 years.