Infantile multilocular renal cyst.

A case of a Japanese 14-month-old male infant with multilocular renal cyst is presented. He was admitted with a chief complaint of an abdominal mass. Although clinically and radiographically multilocular renal cyst in the right kidney was suspected, total nephrectomy was performed because of extreme difficulty of partial nephrectomy and impossibility of complete neglect of malignant cystic tumor. Microscopically, immature glomeruloid tissue, primitive tubules, rhabdomyocytes and nerve fibers were noted. The histological diagnosis of multilocular renal cyst with partially differentiated dysplasia was made. Since the first report by Edmunds in 1892, the etiology of multilocular renal cyst has been discussed for years. In our present case, the pathologic findings suggest that multilocular cystic formation in the right kidney might be the result of developmental disturbances.