Diffuse Bilateral Wilms's Tumor Simulating Multicystic Renal Disease

Wilms's tumor (embryonal adenomyosarcoma) is one of the most common malignant neoplasms in children, constituting 20 per cent of all childhood tumors (1). Four of the 96 cases reported by Gross and Neuhauser (6) were bilateral, but Schneider (11) considered that bilaterality was found in approximately 7 per cent of the patients. The purpose of this article is to report an unusual case of diffuse bilateral infiltration of the kidneys by Wilms's tumor. Case Report R. B., a white boy of thirteen months, was admitted on March 15, 1963, because his mother noticed progressive swelling of the abdomen over a two-month period. The child was born at term after an uneventful pregnancy and an uncomplicated delivery. He had no illnesses prior to admission. On physical examination, two large fixed masses were palpated in the right and left sides of the abdomen. The urine analysis was normal; the urea nitrogen level in the blood was 13 mg. per cent. The blood count was within normal limits (hemoglobin 10.1 gm.), and the child was normotensive. A supine roentgenogram of the abdomen revealed large kidneys. The clinical diagnosis was polycystic kidneys. An excretion urogram (Fig. 1, A) disclosed that both kidneys were markedly enlarged and appeared to be rotated about their anteroposterior axes with the lower poles drawn medially. The left kidney indented and displaced the splenic flexure and the descending colon. The normal architecture of both pelvicalyceal systems was distorted. As seen on the nephrotomogram (Fig. 1, B) , the minor calyces appeared to be relatively undisturbed, but the renal pelves and major calyces showed circular and oval indentations bilaterally. The ureters were symmetrically displaced medially. Roentgenograms of the skeleton were normal. The possibility of leukemic infiltration of the kidneys was considered, but discarded in view of the normal leukocyte count (8,000) and normal appearance of the peripheral blood smear. The roentgen diagnosis of renal involvement by a storage disease could not be supported by clinical or laboratory findings. The possibility that the rotational anomalies of horseshoe kidney were primarily responsible for the appearance of the collecting systems and renal outlines was felt to be remote. A roentgen diagnosis of multicystic horseshoe kidney was made. We were, however, skeptical of the accuracy of this diagnosis because the nephrotomogram failed to demonstrate discrete areas of cyst formation corresponding to the major calyceal deformities. Exploration was planned for the purpose of reducing the size of the distressingly large kidneys by cyst puncture. The child's abdomen was explored. The left kidney was enlarged two to three times and the right kidney eight times the normal size . Both appeared to be lobulated and diffusely involved, but were entirely separate from each other. Biopsies showed Wilms's tumor of both kidneys on frozen and permanent sections. The liver was free of palpable metastases.