INTRAPELVIC WILMS-TUMOR - REPORT OF 2 CASES AND REVIEW OF THE LITERATURE

Wilms tumor arising from the renal parenchyma usually presents initial ly as an abdominal mass. A review of the literature revealed fewer tha n 10 cases manifesting as a renal pelvic mass occupying primarily the collecting system. We have treated 2 patients with this unusual presen tation: 1) a 4-month-old male infant whose initial radiological invest igation demonstrated a left renal neoplasm measuring 10 x 7 x 5 cm.; b isection of the kidney showed a tumor completely filling the collectin g system to the proximal ureter with extreme attenuation of the renal parenchyma, and 2) a 9-year-old boy who was hospitalized due to hematu ria; ultrasonography, computerized tomography and magnetic resonance i maging showed a mass in the right renal pelvis; gross pathology displa yed a 7 x 6 x 5 cm. polypoid mass occupying the renal pelvis without p arenchymal involvement. Microscopically, both lesions were typical Wil ms tumors. We discuss the characteristic clinical manifestations, diag nosis and treatment, and review the literature.