Residual retroperitoneal tumour tissue in patients treated for metastatic non-seminomatous testicular germ cell tumours: an immunohistochemical investigation.

The morphology of resected residual retroperitoneal tumour tissue from 18 patients treated with a combined chemotherapy regime for advanced testicular non-seminomatous germ cell tumours was studied. In five cases (28%) the resected tissue comprised only fibrous tissue and in ten cases (56%) only mature teratoma (T) was present. Embryonal carcinoma (EC) with yolk sac tumour (YST) differentiation was found in addition to T in one case and in two cases the resected tissue comprised pure EC. In all patients with residual T, T had also been present in the primary tumour. Resected tissue containing T was investigated for the presence of various marker proteins, including alpha-1-antitrypsin (A1 AT), carcino-embryonic antigen (CEA), ferritin (FER), lactoferrin (LF), and pregnancy-specific beta-1-glycoprotein (SP1), in addition to the well-established markers for germ cell tumours, alphafetoprotein (AFP) and human chorionic gonadotropin (HCG). AFP and HCG were present in only two cases. A1 AT and CEA were demonstrated in various amounts in epithelial structures in 11 out of 11 cases with T, while FER was found in ten and LF and SP1 in seven cases. Since A1 AT, CEA and LF were also found in the secreted material within the lumen of the teratoid structures, aspiration of cystic fluid for demonstration of these proteins in addition to AFP and HCG is recommended for diagnostic assessment. CEA and SP1 are suggested for localization and treatment of tumour tissue with the recently-developed methods using specific antibodies which are either radiolabelled or conjugated to anti-neoplastic drugs.