Intratubular malignant germ cells in testicular biopsies: clinical course and identification by staining for placental alkaline phosphatase.

This study was undertaken to determine the clinical course of patients with intratubular malignant germ cells (ITMGCs) and to evaluate the reliability of placental alkaline phosphatase (PLAP) for detection of these cells. Eight patients with ITMGCs in testicular biopsy were followed. Four patients received no further immediate treatment. Two of these showed no evidence of disease after 190 and 132 mo; one developed seminoma at 38 mo, and one developed seminoma of the contralateral testis in 61 mo. The remaining four patients underwent immediate orchiectomy. Orchiectomy findings were invasive seminoma in three testes, intratubular seminoma in one, and residual ITMGCs in one testis (one patient had bilateral orchiectomy). Also studied were two testicular biopsies from patients with known retroperitoneal germ cell tumors, respectively, seminoma and teratoma. Both had ITMGCs in their testes. Immunoperoxidase stains for PLAP gave a positive result in all biopsies showing intratubular malignant germ cells. PLAP was not demonstrated in spermatogonia in 471 control biopsies which did not show germ cell neoplasia. Two other patients with incidental seminoma on biopsy for infertility are discussed. These results show that ITMGCs show a high rate of progression to invasive disease, but can show an indolent course. PLAP is a sensitive and specific marker for ITMGC, facilitating diagnosis.