Wilms tumour in a patient with growth hormone replacement therapy.

Wilms tumour was found in a Japanese boy aged 5 years 9 months with isolated growth hormone (GH) deficiency and some congenital anomalies. He had received pituitary GH replacement therapy from the age of 2 years 1 month to 4 years 7 months and after a 1 year interval he received biosynthetic GH for 2 months until the tumour became clinically apparent. This was the sixth known patient with GH deficiency to develop a malignant neoplasm during or after GH replacement therapy and the first with a solid tumour in Japan since 1975, when treatment with pituitary GH for patients with GH deficiency was introduced.