Morphology of testicular germ cell tumours in treated and untreated cryptorchidism.

The histology of 75 testicular germ cell tumours in 73 patients with treated or untreated cryptorchidism was investigated in a group of 503 patients with testicular germ cell tumour and evaluated according to the WHO classification. The proportion of pure seminoma was associated with the height of the testis, being 87% in abdominal. 78% in inguinal and 50% in normally positioned testes. In patients operated upon for cryptorchidism, the current site of the testis seemed to be a more important determinant of this proportion than the original site. The proportion of pure seminoma which developed in testes after successful orchiopexy was equal to that in normally-descended testes (50%) and lower (39%) if orchiopexy had been performed before the age of 16 years. Similarly, among non-seminomas, a higher proportion of tumours containing teratoma tissue was found in cryptorchidism was successfully treated in childhood. It was concluded that a successful orchiopexy in childhood decreases especially the risk of seminoma.