Bone metastases in childhood renal tumours.

Analysis of data from 1434 children with primary renal tumours revealed 57 who developed bone metastases. Of these, 54 were initially recorded as nephroblastoma. Fifty-two of the 57 cases were reviewed histologically, and only 18 were found to be Wilms' tumours. Twenty-three were classified as "Bone-Metastasizing Renal Tumour of Childhood" (BMRTC), and a high male incidence was found for these tumours (M:F=6.7:1). Differences in the pattern of metastasis and the one-year survival between BMRTC and nephroblastoma are discussed. The rarity of bone metastases from true Wilms' tumours is emphasized.