Central nervous system germ cell tumors

The central nervous system is one of the most frequent sites of involvement by extragonadal germ cell tumors. Most of these occur in midline structures, particularly in the sellar region and pineal gland, as well as other sites to a lesser extent (e.g., basal ganglia). The predominant histologic type is germinoma, the intracranial counterpart to the seminoma in the testis and dysgerminoma in the ovary. As in these other sites, germinoma has an exquisite sensitivity to current treatment and an improved prognosis compared to other germ cell tumor components, all of which may occur in the nervous system. Clinical evaluation of these patients involves neuroimaging and analysis of markers in serum and cerebrospinal fluid for diagnosis and to monitor relapse. Recent sequencing efforts have expanded our knowledge of the biology of these tumors and uncovered a high frequency of somatic mutations in members of the KIT/RAS pathways and mTOR/AKT to a lesser extent, in intracranial germ cell tumors, particularly germinoma. In this review we summarize our current knowledge about the clinicopathologic, phenotypic, and molecular characteristics of intracranial germ cell tumors, highlighting specific properties to intracranial sites.