Atypical germ cells preceding metachronous bilateral testicular tumors.

This is the sixth reported case of metachronous testicular neoplasia in which a seminoma has preceded an embryonal carcinoma. Of particular note is the presence of atypical germ cells in the biopsy specimen of the gonad from which the embryonal carcinoma arose. There has developed recently an increasing awareness of germ cell atypia and carcinoma in situ. Pathologists examining testicular biopsies in the infertile patient should be alerted to this process.