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Germinoma

Last Updated: March 27, 2020

Figure 1: The CT (top row left) image for this pineal-region germinoma demonstrates an “engulfed” appearance of the pineal calcification, also visible on GRE (top row right). The ADC image (bottom row left) demonstrates low signal diffusion restriction representing hypercellularity of this tumor. Avid enhancement on T1WI postcontrast image (bottom row right) is typical. This mass is causing obstructive hydrocephalus at the cerebral aqueduct.

Basic Description

  • Intracranial germ cell tumor often occurring in the pineal region (extragonadal seminoma/dysgerminoma)

Pathology

  • WHO grade II (pure germinoma) or grade III (syncytiophoblastic giant cells)
  • Associated with Down and Klinefelter syndromes and NF-1
  • Polygonal primitive germ cells and lymphocytic infiltrates are common microscopic features
  • Single or multiple tumors may occur
    • Multiple tumors are considered metastatic rather than synchronous in the United States

Clinical Features

  • Children and young adults usually afflicted (90% <20 years)
  • Marked male gender predilection (10-33:1) in pineal-region germinomas
  • Females more commonly afflicted 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/CSF β-HCG
  • Treatment: biopsy, low-dose radiation ± chemotherapy
  • Positive prognosticators include mild elevation of β-HCG and pure (WHO II) germinoma histology
  • Invasion and CSF dissemination commonly occur

Imaging Features

  • General
    • Mass within pineal or suprasellar region at or near midline
    • Engulfs pineal gland, may accelerate pineal calcification
    • Basal ganglia uncommonly involved
    • Single or multiple locations (metastatic)
    • Often infiltrates into ventricles, midbrain, thalamus; ± CSF dissemination
  • CT

    • Lobulated, hyperdense mass
    • ± Cysts, hemorrhage
    • Avid, homogeneous enhancement on contrast-enhanced CT ± CSF dissemination
  • MRI

    • T1WI: iso- to hyperintense; normal posterior pituitary “bright spot” may be absent in suprasellar germinoma
    • T2WI: iso- 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
    • MR spectroscopy: elevated Cho, decreased NAA

Imaging Recommendations

  • MRI without and with IV contrast including brain and spine to detect metastases

For more information, please see the corresponding chapter in Radiopaedia.

Contributor: Rachel Seltman, MD

DOI: https://doi.org/10.18791/nsatlas.v1.03.01.17

References

Jinguji S, et al. Factors affecting functional outcomes in long-term survivors of intracranial germinomas: a 20-year experience in a single institution. J Neurosurg Pediatr. 2013;11:454-463.

Liang L, et al. MRI of intracranial germ-cell tumours. Neuroradiology. 2002;44:382-388.

Osborn AG, Salzman KL, Jhaveri MD. Diagnostic Imaging (3rd ed.). Philadelphia, PA: Elsevier, 2016.

Sawamura Y. WHO histological classification of tumors of the central nervous system: germ cell tumors (WHO, 1993). Intracranial Germ Cell Tumors. 1998:3–4.

Ueno T, et al. Spectrum of germ cell tumors: from head to toe. Radiographics. 2004;24:387-404.

Vasiljevic A, et al. Histopathology of pineal germ cell tumors. Neurochirurgie. 2015;61(2-3):130-137.

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