- Intracranial germ cell tumor, often occurring in the pineal region (extragonadal seminoma/dysgerminoma)
- WHO grade II (pure germinoma) or grade III (syncytiotrophoblastic giant cells)
- Associated with Down and Klinefelter syndromes and neurofibromatosis type 1 (NF-1)
- Polygonal primitive germ cells and lymphocytic infiltrates are common microscopic features
- Single or multiple tumors can occur
- Multiple tumors are considered metastatic rather than synchronous in the United States
- Children and young adults usually afflicted (90% are <20 years old)
- Marked male gender predilection (10–33:1) in pineal-region germinomas
- Females afflicted more commonly with suprasellar germinomas
- Common presenting signs/symptoms
- Pineal region: headache due to mass effect on tectum and ventricular obstruction at the cerebral aqueduct, Parinaud syndrome (upgaze palsy)
- Suprasellar: endocrine dysfunction (diabetes insipidus, precocious puberty), visual field defects
- Laboratory findings: increased serum/cerebrospinal fluid (CSF) beta-human chorionic gonadotropin (β-hCG) level
- Treatment: biopsy, low-dose radiation ± chemotherapy
- Positive prognosticators include mild elevation of β-hCG level and pure (WHO grade II) germinoma histology
- Invasion and CSF dissemination commonly occur
- Mass within pineal or suprasellar region at or near midline
- Engulfs pineal gland, can accelerate pineal calcification
- Basal ganglia uncommonly involved
- Single or multiple locations (metastatic)
- Often infiltrates into ventricles, midbrain, thalamus; ±CSF dissemination
- Lobulated, hyperdense mass
- ±Cysts, hemorrhage
- Avid, homogeneous enhancement on contrast-enhanced CT ± CSF dissemination
- T1WI: isointense to hyperintense; normal posterior pituitary “bright spot” may be absent in suprasellar germinoma
- T2WI: isointense to hyperintense; foci of hemorrhage appear hypointense; hyperintense areas of cysts or necrosis
- FLAIR: mildly hyperintense
- DWI: diffusion restriction due to hypercellularity
- T1WI+C: avid, homogeneous enhancement including areas of CSF dissemination and parenchymal invasion
- MRS: elevated Cho, decreased NAA
- MRI without and with intravenous contrast including brain and spine to detect metastases
For more information, please see the corresponding chapter in Radiopaedia.
Contributor: Rachel Seltman, MD
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