The external metastasis of the central nerve system germ cell tumors: case report and review of the literature

Background Central nervous system germ cell tumors (CNS GCTs) represent a class of rare tumors that exhibit region-specific prevalence in some Asian areas (15.3%), higher than that in North America (3.6%), and age-specific prevalence in children and adolescents. According to the 2016 World Health Organization (WHO) classification, CNS GCTs can be categorized into germinomas and non-germinomatous GCTs (NGGCTs). Owing to the compression of the interventricular foramen by enlarged GCTs in the pineal gland, the resultant obstructive hydrocephalus may result in high intracranial pressure (HIP) at an alarming pace, which urgently requires a ventriculoperitoneal shunt for the relief of severe HIP. Although CNS GCT cells tend to migrate through the cerebrospinal fluid (CSF) starting from the subependymal lining, metastasis along the ventriculoperitoneal shunt tube is extremely rare. Case presentation In this study, we reported two cases of iGCTs with intraperitoneal metastasis. Both patients underwent ventriculoperitoneal shunt placement to alleviate HIP, and both received standard radiotherapy and chemotherapy, but they still developed abdominal metastasis, and all the abdominal masses were pathologically confirmed to be iGCTs. Conclusions We performed a literature study and found that from 1979 to 2020, a total of 18 cases of iGCTs were metastasized outside the nervous system. We also found a shift of the median of 13.5 months and that the most common primary site was the pineal region (83.3%); moreover, nearly half of the patients (44%) died within 1 year of metastasis, indicating a poor prognosis after celiac metastasis.