Gliomatosis cerebri is a rare, diffusely infiltrative glial tumour that involves at least three lobes by definition. There often is an important discordance between clinical and radiological findings, as it may be clinically silent while it appears as a very extensive process radiologically.
- peak incidence is 20-40 years of age
- M:F of 1.5:1 in one sequential series of 54 patients 7
The tumour may be primary (de novo) or secondary, with the latter as a result from the spreading of a more focal glioma 5. Gliomatosis cerebri can contain areas of WHO grade 2 or 3 tumours, and rarely grade 4 6,7.
Gliomatosis cerebri can be divided into two types 7:
- type 1: no discrete mass
- type 2: discrete mass with further diffuse CNS involvement
- IDH1 mutation more common in this subtype 7
CT can be normal because lesions often isodense to normal brain parenchyma. There is relative lack of mass effect and distortion. There may be an ill-defined asymmetry or subtle hypoattenuation to the involved brain parenchyma.
Mass effect and enhancement are minimal. There is loss of gray-white matter differentiation and diffuse gyral thickening.
Diffuse T1 and T2 prolongation throughout both white and grey matter:
- T1: iso to hypointense to grey matter 1
- T2: hyperintense to grey matter 1
- T1C+: typically no or minimal enhancement
- DWI: usually no restriction
- elevated Cho:Crn and Cho:NAA ratios 2
- marked elevation of myoinositol (mI)
- low/normal rCBV: correlates with no vascular hyperplasia
- FDG PET shows marked hypometabolism
Treatment and prognosis
The condition carries a poor prognosis with an average survival of ≈ 50% at 1 year and 25% at 3 years. Transformation into glioblastoma may occur a few years later.
Surgery is not a suitable option due the diffuse nature of this tumour but can be used to treat complications such as hydrocephalus.
Radiation therapy has been shown to increase survival 7, however, the large field usually required in these lesions increases the risk of severe toxicity 5. Chemotherapy is a treatment option, although there is a lack evidence in its use (both positive and negative) 7.
General imaging differential considerations include 6:
- progressive multifocal leukoencephalopathy (in immunocompromised patient): no mass effect
- multicentric glioblastoma: may be indistinguishable
- primary CNS lymphoma: usually vividly enhancing
- encephalitis: different clinical presentation
- WHO classification of CNS tumours
- diffuse astrocytic tumours
- diffuse astrocytoma grading
- low grade astrocytoma
- anaplastic astrocytoma
- glioma treatment response assessment in clinical trials
- multicentric glioblastoma
- multifocal glioblastoma
- O6-Methylguanine-DNA methyltransferase (MGMT)
- isocitrate dehydrogenase 1 (IDH1)
- giant cell glioblastoma
- gliomatosis cerebri
- radiation-induced gliomas
- localised astrocytic tumours
- specific locations
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- 7. Chen S, Tanaka S, Giannini C et-al. Gliomatosis cerebri: clinical characteristics, management, and outcomes. J. Neurooncol. 2013;112 (2): 267-75. doi:10.1007/s11060-013-1058-x - Free text at pubmed - Pubmed citation