Giant cell glioblastoma

Last revised by Dr Richard Gagen on 15 Oct 2022

Giant cell glioblastoma is a classic variant of glioblastoma (along with epithelioid glioblastoma and gliosarcoma) and although not distinct diagnoses, they continue to be recognized in the current (2021) WHO classification of CNS tumors 8. This tumor was previously called monstrocellular tumor due to the large size of its cells.

This neoplasm represents ~5% of GBM cases 1, with wider age range with a tendency to affect younger individuals than does conventional GBM 3, and accounts for about 1% of primary brain tumors.

The clinical features are similar to glioblastoma in general and patients could present a focal neurological deficit, symptoms of increased ICP, and seizures.

Giant cell glioblastomas are usually encountered in the cerebral hemispheres but can occur at any site in the central nervous system. There are some reports of extradural 6 and spinal leptomeningeal 5 metastases. 

As is the case with some gliosarcomas, giant cell glioblastomas often have abundant connective tissue resulting in firm and circumscribed tumors reminiscent of cerebral metastases or even meningiomas 7. In other instances, connective tissue is minimal and appearances are indistinguishable from glioblastomas

Giant cell glioblastoma is defined as a glioblastoma with a marked predominance of bizarre multinucleated giant cells that can be up to 0.5mm in diameter 1,7.

This tumor contains a high frequency of TP53 mutations (70-90%) and less commonly PTEN mutations (33%) and TERT mutations (25%) 2,7. EGFR amplification and IDH mutations are rare (i.e. they are IDH wild-type) 7

Giant cell glioblastomas have no distinguishing features when compared to runofthemill glioblastoma 4.

Giant cell glioblastoma overall survival is superior when compared to patients with conventional IDH wild-type glioblastoma, although it remains poor with only ~10% 5-year survival and a median survival of 11 to 13 months 1,3,7.

This tumor was first described by Alexander Schmincke (1877-1953), a German pathologist 1.

On imaging the differential is primarily: 

Histologically, pleomorphic xanthoastrocytoma (PXA) is one important differential diagnosis, as both have in common the presence of giant tumor cells, infiltration of lymphocytes, deposition of reticulin and gross circumscription 4. Neuronal markers, positive in PXAs, are negative in giant cell glioblastomas. 

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