Giant cell glioblastoma
Giant cell glioblastoma is a variant of glioblastoma (along with epithelioid glioblastoma and giant cell glioblastoma) recognized in the current (2016) WHO classification of CNS tumors . This tumor was previously called monstrocellular tumor due to the macro size of its cells.
This neoplasm represents ~5% of GBM cases , with wider age range with a tendency to affect younger individuals than does conventional GBM , 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 and spinal leptomeningeal 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 . 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 .
This tumor contains a high frequency of TP53 mutations (70-90%) and less commonly PTEN mutations (33%) and TERT mutations (25%) . EGFR amplification and IDH mutations are rare (i.e. they are IDH wild-type) .
Giant cell glioblastomas has no distinguishing features when compared to the glioblastoma .
Treatment and prognosis
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 .
History and etymology
This tumor was first described by Alexander Schmincke (1877-1953), a German pathologist .
On imaging the differential is primarily:
- conventional glioblastoma: usually indistinguishable
- cerebral metastases
- meningioma: if abutting the dura
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 . Neuronal markers, positive in PXAs, are negative in giant cell glioblastomas.