Imaging Features of Rhabdoid Tumor of the Kidney in Children

PURPOSE: To evaluate the difference in radiologic features of rhabdoid tumor of the kidney (RTK) in children according to the location of the tumor within the kidney. MATERIALS AND METHODS: We retrospectively reviewed the radiologic findings of pathologically confirmed RTK in seven children (5 boys and 2 girls; age range, 6 months to 4 years 8 months; median, 18 months). All subjects underwent abdominal CT. We analyzed tumor location, size, and margin; renal hilar involvement, subcapsular hematoma, calcification, necrosis, and lymphadenopathy. RTK was classified according to the location of the tumor within the kidney: A tumor that mainly located in the central portion of the kidney with or without peripheral extension was described as type I, while one located at the periphery was type II. Imaging findings between the two types were compared. RESULTS: Tumor size varied from 3 cm to 12 cm. Tumor outlines were ill-defined in four cases but relatively well-defined in three. Four tumors (57 %) were type I. Hilar involvement was found in all four and a small subcapsular hematoma in one. Three tumors (43%) were type II, and in all three, large crescent-shaped subcapsular hematomas were found. CONCLUSION: Centrally located RTK showed hilar involvement with a small subcapsular hematoma, while in cases of peripherally located RTK, a large subcapsular hematoma was present. These findings may be helpful for the differential diagnosis of other pediatric renal tumors.