Bone-metastasizing primary renal tumors in children

Six cases of childhood renal tumor with extensive bone involvement are reported. The neoplasms had been classified originally as Wilms tumor with atypical clinical and pathologic features. Subsequent to a retrospective histologic analysis, the lesions were reclassified as follows: three cases as bone-metastasizing renal tumors of childhood, one case as rhabdomyosarcoma, one case as undifferentiated sarcoma, and one case as undifferentiated malignant neoplasm.