Gliomatosis cerebri is a rare growth pattern of diffuse gliomas 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.
Importantly, whereas gliomatosis was previously considered a distinct entity, since the 2016 update to the WHO classification of CNS tumours it is now merely thought of as a growth pattern 8.
- 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 II or III tumours and rarely grade IV 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+ (Gd): 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 lack of evidence in its use (both positive and negative) 7.
General imaging differential considerations include 6:
progressive multifocal leukoencephalopathy
- in an immunocompromised patient
- no mass effect
- may be indistinguishable
primary CNS lymphoma
- usually vividly enhancing
- different clinical presentation
- WHO classification of CNS tumours
- WHO grading of CNS tumours
- VASARI MRI feautre set
- diffuse astrocytic tumours
- prognostic markers
- diffuse astrocytoma grading
- low grade astrocytoma
- anaplastic astrocytoma
- glioblastoma variant
- glioblastoma vs cerebral metastasis
- treatment response
- Stupp protocol
- glioma treatment response assessment in clinical trials
- multicentric glioblastoma
- multifocal glioblastoma
- radiation-induced gliomas
- gliomatosis cerebri (growth pattern)
- 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
- 8. Louis DN, Perry A, Reifenberger G et-al. The 2016 World Health Organization Classification of Tumors of the Central Nervous System: a summary. Acta Neuropathol. 2016;131 (6): 803-20. doi:10.1007/s00401-016-1545-1 - Pubmed citation