Expression of human chorionic gonadotropin in testicular germ cell tumors

Background: We have shown that most patients with seminomas have elevated serum concentrations of the free beta subunit of human chorionic gonadotropin (hCG beta) and that in nonseminomatous testicular cancer, most of the hCG in the serum is hyperglycosylated (hCG-h). However, the tissue expression of hCG-h or hCG beta in germ cell tumors (GCTs) has not been reported. Our objective was to study the expression and diagnostic value of hCG-h and hCG beta in testicular GCTs. Methods: We studied the immunohistochemical expression of hCG, hCG-h, hCG beta, and the free a subunit of hCG (hCa alpha) in GCTs from 154 patients. We compared the tissue expression with serum concentrations and evaluated the correlation between staining intensity, established prognostic variables, and outcome. Results: The expression varied between tumor types. All forms of hCG, including hCG-h, were detected in embryonal carcinomas (22%) and mixed GCTs (48%). Polyclonal hCG and monoclonal hCG beta antibodies detected immunoreactivity in some seminomas (7%). No form of hCG was found in spermatocytic seminomas, pure teratomas, or a yolk sac tumor. The serum concentrations correlated with the corresponding tumor expression. The staining intensities of hCG, hCG beta, hCG-h, and hCG alpha correlated with disease stage but not significantly with relapse, disease-related mortality, or progression-free survival. Conclusion: Trophoblastic tissue expresses hCG, hCG-h, and free subunits together whereas seminoma tissue occasionally expresses hCG beta. This difference might aid in differential diagnosis of some difficult-to-classify cases. (C) 2014 Elsevier Inc. All rights reserved.