Cystic partially differentiated nephroblastoma: a clinicopathologic entity in the spectrum of infantile renal neoplasia.

Three cases of cystic partially differentiated nephroblastoma (CPDN) are presented and ten cases from literature are reviewed. CPDN has been designated by various terms; it is a cystic encapsulated tumor occurring before 2 years of age. Cysts are lined by epithelium; septa of the cysts show a mixture of partially differentiated and undifferentiated metanephrogenic blastema. This histologic feature distinguishes CPDN from multilocular cyst of kidney. In seven cases simple nephrectomy, and in remaining cases nephrectomy with radiation and/or chemotherapy, had been the treatment. The disease-free interval ranged from 5 to 72 months, without reports of recurrence or metastasis. CPDN appears to take a benign course and simple nephrectomy seems to be the treatemtn of choice. However, in view of the possibility of recurrence as shown in rare instances by congenital mesoblastic nephroma, another less aggressive lesion in the spectrum of infantile renal neoplasia, regular follow up is recommended.