Abstract

Twin boys, both of whom had hypospadias and bilateral cryptorchidism, each developed a left-sided Wilms's tumour. The first twin was found to have an advanced multifocal tumour at the age of 15 months and died with local recurrence and pulmonary metastases. The diagnosis was made in the second twin one month later and at nephrectomy the tumour was found to be encapsulated without metastases; he is disease-free 12-years later. Although the histological appearances were similar in each twin, the tumours did not develop at the same rate and did not show the 'mirror-image' pattern suggested for embryonal tumours in identical twins.