Purpose: We designed this study to differentiate the clinical presentation, particularly the incidence of hematuria, of a rhabdoid tumor of the kidney (RTK), a rare but highly malignant tumor, from a Wilms tumor.
Patients and methods: We reviewed patient flow charts from the National Wilms Tumor Study Group and queried participating hospitals to obtain additional information regarding presenting symptoms and laboratory data for fifty patients. Patient ages ranged from 2 days to 3.5 years with a mean of 11 months. We documented the presence of gross and microscopic hematuria, fever, and hypercalcemia.
Results: Whereas 75% of children with rhabdoid tumor of the kidney (RTK) had stage III (44%), IV (27%), or V (4%) tumors, 67% of children with Wilms tumors had stage I (41%) or II (26%) tumors. Either gross or microscopic hematuria was present in 84.4% (27/32) of the patients with RTK. Gross hematuria was present in 59% (22/37) of children with RTK compared with 18% previously reported with Wilms tumor. Microscopic hematuria was present in 76% (22/29) of children with RTK compared with 24% previously reported with Wilms tumor. Fever was found in 44% (16/36) of children with RTK, compared with 22% of children previously reported with Wilms tumor. Hypercalcemia was seen 26% (6/23) of children with RTK.
Conclusion: Although diagnosis of any renal mass still must be confirmed with histopathologic features, a distinct clinical presentation with fever, hematuria, a young age, and high-tumor stage at presentation suggests the diagnosis of RTK.