Prognostic implications of distinctive imaging characteristics in primary intracranial germ cell tumors: A retrospective analysis

Primary central nervous system (CNS) germ cell tumors (GCTs) are rare brain tumors that encompass two subtypes: germinomas and non-germinomatous germ cell tumors (NGGCTs), NGGCTs have less favorable outcome and require multi-modality treatment. Biopsy is recommended for disease diagnosis, the specimen may not adequately reflect the entire tumor. This study aimed to assess distinct imaging characteristics to differentiate between GCT subgroups and to identify possible initial image and subgroup features that influence survival. This retrospective study, conducted from January 2006 to March 2023, analyzed patient data and MRI findings of primary CNS GCTs. It evaluated tumor characteristics including cysts, seeding, multifocality, and hemorrhage. Tumor volumes and apparent diffusion coefficient (ADC) values of both tumoral and normal-appearing contralateral white matter were measured. These factors were correlated with overall and 5-year survival rates. This study included 51 participants with CGTs, comprising 19 germinoma and 32 NGGCTs cases. GCTs with hemorrhage had worse overall (P = 0.03) and 5-year (P = 0.01) survival rates. No survival difference between germinoma and non-hemorrhagic NGGCT. NGGCTs were more likely to bleed (P < 0.001) than germ cell tumor, especially those with choriocarcinoma or yolk sac tumor components (P = 0.001). The ADC ratios of germinomas were significantly lower than those of NGGCTs (P = 0.03 for whole tumor; P < 0.01 or solid part), The ADC ratios of choriocarcinoma were also lower than mixed tumor (P = 0.01; P = 0.02). Hemorrhage indicates worse prognosis. Intratumoral hemorrhage and ADC ratios differentiate germinoma from NGGCTs. Larger cohorts and advanced MR techniques are needed for future study.