Carcinoma in situ of germ cells and subsequent development of an invasive seminoma in a hyperprolactinaemic man.

A 25-year-old man was first seen complaining of impotence and found to have a pituitary tumour and hyperprolactinaemia. Both testes were small and atrophic, but a testicular tumour was not apparent. Biopsy of the right testis was performed, and the pathology report described thickening of the seminiferous tubule walls and impaired spermatogenesis. The patient refused to undergo an operation for his pituitary tumour and was lost to follow-up. 5 years later, the same patient presented with enlargement of his right testis, and this and the pituitary tumour were excised. The testicular tumour was classified as seminoma, and the pituitary tumour as an adenoma with low malignancy. Re-examination of the previous specimen of his right testis revealed foci of carcinoma-in-situ. This is an additional example of the growth of an invasive germ cell tumour from non-invasive carcinoma-in-situ of the testis.