Primary renal tumours in the first year of life. A population based review.

Of 30 patients presenting with primary renal tumours in the first year of life, there were 23 Wilms' tumours (15 classical, six epithelial and two rhabdomyomatous), three rhabdoid neoplasms and four mesoblastic nephromas. Criteria for the diagnosis of rhabdoid tumours and mesoblastic nephromas are discussed with reference to histological difficulties. Although Wilms' tumour was the commonest neoplasm, mesoblastic nephroma predominated in the first three months of life. The clinical behaviour of the cases is reviewed, and rhabdoid tumours, although relatively few in number, accounted for a significant part of the overall mortality.