Intracranial germ cell tumours. A review with special reference to endocrine manifestations.

EPIDEMIOLOGY: Intracranial germ cell tumours (icGCTs) represent 3-15% of primary paediatric intracranial neoplasms with a considerable geographical variation in incidence. Ninety percent of patients diagnosed with icGCTs are under 20 years of age. PATHOLOGY: Histologic characteristics and investigation of the tumour markers β-human chorionic gonadotropin (β-hCG) and alpha-fetoprotein (AFP) help define the different categories of icGCTs. The tumours are divided into two major groups called germinomas and non-germinomatous GCTs (NGGCTs). CLINICAL
PRESENTATION: The clinical symptoms depend on the size and location of tumour in the brain, which is most commonly in the pineal or suprasellar region. Pineal GCTs often present with neurological symptoms because of their tendency to cause increased intracranial pressure. Suprasellar GCTs are often accompanied by endocrine abnormalities such as diabetes insipidus (DI), growth retardation and precocious or delayed puberty. DIAGNOSIS: A combination of clinical findings, endocrine and tumour marker evaluation, spinal fluid cytology, magnetic resonance imaging (MRI) and biopsy helps verifying the diagnosis of an icGCT. A summary of published data (n = 97) revealed that >90% of patients at diagnosis had at least one endocrine abnormality, DI being the most common (>80%). TREATMENT: Classification of tumour is important for choice of treatment and for prognosis. A combination of chemotherapy and radiotherapy is often used, since most icGCTs have a great sensitivity to these treatment modalities.
CONCLUSION: Endocrine symptoms are very frequently appearing in patients with icGCTs and they can present long before neuroimaging verification of tumour is possible. It is of the outmost importance to have the diagnosis of icGCTs in mind when children, adolescents and young adults are presenting with endocrine irregularities, because most icGCTs are very sensitive to radiotherapy and chemotherapy, and early onset of treatment is important in order to minimize morbidity and mortality.