Intrapelvic wilms’ tumor - report of two cases and review of the literature

Abstract

Wilms’ tumor is the most common solid tumor in children and often presents as an abdominal mass. In most cases, it involves the renal parenchyma and in later stage invades renal pelvis. Two cases of renal tumor filled entirely of the renal collecting system without parenchymal invasion are reported. Case 1 was a 4 month old male baby who was found to have large abdominal mass. Echogram revealed a left lobulated renal mass, measuring 10 × 7.2 × 5.2 cm without calcification or necrosis. Bisection of the renal mass revealed a markedly dilated renal pelvis and calices filled by a glistening and delicate renal pelvic tumor with yellow granular appearance. The entire tumor can be lifted away from the attenuated renal parenchyma from which a thin stalk is noted at midportion. Case 2 was a 9 year old boy who was noted to have gross hematuria and right flank pain off and on for several months. Echogram revealed that the right kidney is (12.3 × 6.5 cm) slightly larger than the left (10.2 × 5.3 cm). However, a hyperechoic mass measuring 8.3 × 5.4 × 6.1 cm was noted occupying the dilated renal pelvis. Histologic examination disclosed that both tumor masses are composed of epithelial, stromal and blastemal components. The surface is covered by transitional epithelium. The renal parenchyma is not involved by the tumor. The renal cortex is extremely attenuated in one case. In reviewing the literature, there are less than 10 cases of Wilms’ tumor occurring entirely in the renal pelvis. With the aids of echogram, CT and MRI, differentiation from other renal neoplasm can be achieved. It is important to note that unnecessary surgical exploration of the renal pelvis before nephrectomy should be avoided in order to prevent tumor spillage. Wilms’ tumor is the most common solid tumor in children and often presents as an abdominal mass. In most cases, it involves the renal parenchyma and in later stage invades renal pelvis. Two cases of renal tumor filled entirely of the renal collecting system without parenchymal invasion are reported. Case 1 was a 4 month old male baby who was found to have large abdominal mass. Echogram revealed a left lobulated renal mass, measuring 10 × 7.2 × 5.2 cm without calcification or necrosis. Bisection of the renal mass revealed a markedly dilated renal pelvis and calices filled by a glistening and delicate renal pelvic tumor with yellow granular appearance. The entire tumor can be lifted away from the attenuated renal parenchyma from which a thin stalk is noted at midportion. Case 2 was a 9 year old boy who was noted to have gross hematuria and right flank pain off and on for several months. Echogram revealed that the right kidney is (12.3 × 6.5 cm) slightly larger than the left (10.2 × 5.3 cm). However, a hyperechoic mass measuring 8.3 × 5.4 × 6.1 cm was noted occupying the dilated renal pelvis. Histologic examination disclosed that both tumor masses are composed of epithelial, stromal and blastemal components. The surface is covered by transitional epithelium. The renal parenchyma is not involved by the tumor. The renal cortex is extremely attenuated in one case. In reviewing the literature, there are less than 10 cases of Wilms’ tumor occurring entirely in the renal pelvis. With the aids of echogram, CT and MRI, differentiation from other renal neoplasm can be achieved. It is important to note that unnecessary surgical exploration of the renal pelvis before nephrectomy should be avoided in order to prevent tumor spillage.