Neonatal renal tumours.

Neonatal renal tumours are rare, with only 7% of all neonatal tumours arising from the kidney. Presentation is usually as a flank mass or as a coincidental finding on either antenatal or postnatal ultrasound. Mesoblastic nephroma is the most common tumour to be found at this age, but Wilms' tumour and other malignant and benign tumours occur. Cross sectional imaging is useful to delineate the extent of the disease. Given the low malignant potential of these tumours, treatment is by radical nephroureterctomy, except in cases with bilateral disease or syndromic patients with a high incidence of metachronous tumours. Chemotherapy is rarely indicated. Survival is generally excellent for all tumour types in this age group, the exception being malignant rhabdoid tumour of the kidney which may have metastases at presentation.