Cystic partially differentiated nephroblastoma and polycystic Wilms tumor: a spectrum of related clinical and pathologic entities.

Cystic partially differentiated nephroblastoma is a rare neoplasm occurring in young children and demonstrating features of classic nephroblastoma (Wilms tumor) and multilocular cysts. Cystic partially differentiated nephroblastoma actually represents a spectrum of cystic renal tumors in which varying amounts of blastema, stroma and epithelial structures are present. Some of these lesions should, perhaps, be classified more accurately as polycystic nephroblastoma. The clinical and pathologic findings, and management of 2 infants with cystic partially differentiated nephroblastoma are presented. The controversy over the histogenesis of these lesions and whether they should be considered benign or potentially malignant is discussed.