Carcinoma-in-situ testis in patients with assumed extragonadal germ-cell tumours

Testicular biopsies were done in 15 consecutive patients who were believed to have extragonadal germ-cell tumours. 8 patients (53%) had carcinoma-in-situ (CIS) in the gonads, although none had clinical signs of tumour. In addition, 3 of these patients had small areas of invasive tumour growth. Germ-cell tumours can only be diagnosed as being extragonadal in origin if testicular biopsy appearances are normal.