Intratubular malignant germ cells (carcinoma in situ) accompanying invasive testicular germ cell tumors.

We examined 111 radical orchiectomy specimens from patients with germ cell tumors of the testis treated between 1971 and 1981 for the presence of intratubular malignant germ cells (so-called carcinoma in situ) in adjacent testicular tissue. Of the specimens 12 were unevaluable because the entire specimen was tumor, while 36 of 44 cases of pure seminoma (82 per cent) and 41 of 55 mixed or nonseminomatous tumors (75 per cent) had intratubular malignant germ cells. Of the 22 cases without intratubular malignant germ cells 10 had severe atypia that suggested an earlier or borderline stage of development. These data support the contention that germ cell tumors originate as intratubular neoplasms or so-called carcinoma in situ in the seminiferous tubules.