Diagnostic evaluation of suspected intracranial germ cell tumors (GCTs)

MRI: magnetic resonance imaging; CNS: central nervous system; AFP: alpha-fetoprotein; hCG: human chorionic gonadotropin; CSF: cerebrospinal fluid.

* Usual cutoffs for elevation are AFP >10 ng/mL (or above institutional range) and hCG >50 milli-international units/mL. Elevation in either compartment (serum or CSF) is considered abnormal.

¶ If preoperative lumbar puncture is not safe due to obstructive hydrocephalus or mass effect, ventricular CSF can sometimes be sampled at the time of biopsy to assess CSF tumor markers; however, ventricular CSF is unreliable for determining metastatic status.

Δ A tissue diagnosis is required for most intracranial GCTs. Potential exceptions include suspected bifocal germinoma with negative tumor markers and patients with high-level AFP or hCG elevation. Refer to UpToDate topic on intracranial GCTs for more information.

◊ The initial surgical management of suspected intracranial GCTs differs from that of many other primary brain tumors, in that maximal safe resection is usually not undertaken as the initial procedure. A biopsy is the initial procedure of choice in most cases, followed by "second-look" surgery as appropriate. Refer to UpToDate topic on intracranial GCTs for more information.