Molecular and histopathological characterization of seminoma patients with highly elevated human chorionic gonadotropin levels in the serum.

Approximately 30% of seminoma (SEM) patients present with moderately elevated human chorionic gonadotropin (hCG) levels at first diagnosis. In case of high hCG serum levels, the presence of a non-SEM component, i.e. choriocarcinoma (CC), may be assumed. To characterize cases described as pure seminoma with high serum hCG levels, tissue samples and DNA were analyzed. Patient files from an international registry were screened for patients with SEM and extraordinarily high hCG serum levels. IHC and qRT-PCR analysis was performed for markers of SEM, embryonal carcinoma (EC) and CC/trophoblast cells. The cell lines TCam-2 (SEM), 2102EP, NCCIT, NT2/D1 (EC) and JAR, JEG3 and BeWo (CC) were included for comparison. Of 1031 SEM patients screened, 39 patients (3.7%) showed hCG serum levels > 1000 U/l. Of these, tumor material for IHC and RNA for qRT-PCR was available from n = 7 patients and n = 3 patients, respectively. Median pre-orchiectomy serum hCG level was 5356 U/l (range: 1224-40909 U/L). Histopathologically, all investigated samples were classified as SEM with syncytiotrophoblast sub-populations. SEM cells were SALL4