Epidemiology, natural history, and optimal management of neurohypophyseal germ cell tumors

OBJECTIVE Intracranial germ cell tumors (iGCTs) often arise at the neurohypophysis, their second most common origination, following the pineal region. Neurohypophyseal iGCTs present with stereotypical symptoms, including pituitary dysfunction and visual field deficit, due to their suprasellar location. The goal of this study was to present a large, longi- tudinal single-institution experience with neurohypophyseal iGCTs to better understand their natural history and identify opportunities for further improvement in treatment outcomes. METHODS This is a retrospective, single-institution cohort study of neurohypophyseal iGCTs treated between 1988 and 2017, with a focus on the epidemiology, presentation, natural history, and treatment. RESULTS Thirty-five neurosurgically managed patients met inclusion criteria; the median age was 18 years (3 months to 49 years), and 74% of patients were male (n = 26). Thirty-one tumors were germinomas, and 4 were nongerminomatous iGCTs. Presenting symptoms included pituitary insufficiency in 76% (n = 25), visual deficit in 45% (n = 15), and dia- betes insipidus (DI) in 61% (n = 20) of patients. Index symptoms included isolated DI in 10 (36%), isolated hormone deficiency in 14 (50%), and concomitant DI and hormone deficiency symptoms in 4 (14%). Radiographic diagnostic latency was common, occurring at a median of 363 days (range 9-2626 days) after onset of the first symptoms and was signifi- cantly associated with both DI and hormone deficiency as the index symptoms (no DI vs DI: 360 vs 1083 days, p = 0.009; no hormone deficiency vs hormone deficiency: 245 vs 953 days, p = 0.004). Biochemical abnormalities were heteroge- neous; each pituitary axis was dysfunctional in at least 1 patient, with most patients demonstrating at least 2 abnormali- ties, and pretreatment dysfunction demonstrating a nonsignificant trend toward association with long-term posttreatment hormone supplementation. Among germinomas, whole-brain or whole-ventricle radiotherapy demonstrated significantly improved progression-free and overall survival compared with local therapy (p = 0.009 and p = 0.004, respectively). CONCLUSIONS Neurohypophyseal iGCTs are insidious tumors that may pose a diagnostic dilemma, as evidenced by the prolonged latency before radiographic confirmation. Serial imaging and close endocrine follow-up are recommended in patients with a characteristic clinical syndrome and negative imaging, due to the propensity for radiographic latency. Pretreatment biochemical abnormalities may indicate higher risk of posttreatment pituitary insufficiency, and all patients should receive careful endocrine follow-up. Local radiotherapy is prone to treatment failure, while whole-ventricle treatment is associated with improved survival in germinomas.

Automated summary

Intracranial germ cell tumors (iGCTs) originating from the neurohypophysis, the second most common site after the pineal region, present with stereotypical symptoms such as pituitary dysfunction and visual field deficit. Radiographic diagnostic latency is common and associated with index symptoms of diabetes insipidus (DI) and hormone deficiency. Pretreatment biochemical abnormalities may indicate a higher risk of posttreatment pituitary insufficiency. Whole-brain or whole-ventricle radiotherapy shows improved survival in germinomas compared to local therapy.