Multinodular and vacuolating neuronal tumor
Citation, DOI & article data
Multinodular and vacuolating neuronal tumors (MVNT) are lesions with a distinct cytoarchitectural pattern.
Radiologically, MVNTs appear as small 'bubbly' indolent subcortical tumors that sometimes present with seizures. These tumors have been most frequently identified in the temporal lobe, although that is likely to be due to that location being more likely to result in seizures than necessarily a predilection for that lobe 1-4.
Lesions with identical imaging features have been described in the cerebellum but have not been histologically confirmed and have, therefore, prudently been named multinodular and vacuolating posterior fossa lesions of unknown significance (MV-PLUS) 7.
The true epidemiology of these tumors is unknown as they have only been relatively recently described and most are asymptomatic, so are likely undiagnosed or misdiagnosed as other lesions (see differential diagnosis below) further confounding epidemiology.
Reported cases are mostly in young to middle-aged individuals with adult-onset epilepsy, or identified incidentally 1-4,7.
Other than some of these lesions being epileptogenic, it is likely that most are asymptomatic as presenting symptoms are usually difficult to reconcile with the lesion location 1-4,7.
MVNTs are considered as one of the glioneuronal and neuronal tumors in the current (2021) WHO classification of CNS tumors 9.
The histopathological hallmark of MVNT is of neuroepithelial cells with conspicuous stromal vacuolation arranged in nodules principally within the deep cortical ribbon and superficial subcortical white matter 1-3.
Alterations in the MAPK pathway are important molecular characteristics 9.
Smaller lesions are difficult to identify, but if seen will appear as non-enhancing low attenuation lesions deep to the cortex in the subcortical white matter.
These tumors appear as a cluster of well-circumscribed high T2 signal 'bubbles' located predominantly in the subcortical white matter but can involve the overlying cortex 1,3,4.
T1: hypointense to adjacent gray and white matter
T1 C+ (Gd)
usually no enhancement
some faint focal enhancement may be seen 3,4
hyperintense to grey and white matter, almost as high as CSF
occasional central hypointense dot (also hypointense on FLAIR) 7,8
FLAIR: does not suppress (remains high signal)
In the cerebellum (MV-PLUS) these lesions most commonly involve the vermis, often extending cerebellar hemispheres, but not the brainstem 7.
Treatment and prognosis
MVNTs appear to be benign tumors with very indolent biological behavior which can, if asymptomatic, be followed by imaging alone. In symptomatic patients (where the MVNT is causing seizures) surgical resection often controls seizures, with no tumor regrowth reported 1-4.
History and etymology
MVNTs were first described in 2013 3 and included in the 2016 revised 4th edition of the WHO classification of CNS tumors as an "architectural pattern" but recognized as a distinct entity in the 2021 5th edition 9.
Possible considerations include
can appear similar but usually is mostly cortical (rather than subcortical)
often has bright FLAIR rim
focal cortical dysplasia (type II)
high T2 signal deep to the cortex is in the same location but is usually associated with a radial glial band (transmantle sign) and with thickened abnormal overlying cortex
location can be similar
usually more elongated along vessel long axis
fully attenuating on FLAIR
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- 8. Badat N, Savatovsky J, Charbonneau F, Collin A, Lecler A. Multinodular Vacuolating and Neuronal Tumor of the Cerebrum. Neurology. 2017;89(3):304-5. doi:10.1212/WNL.0000000000004123 - Pubmed
- 9. Louis D, Perry A, Wesseling P et al. The 2021 WHO Classification of Tumors of the Central Nervous System: A Summary. Neuro-Oncology. 2021;23(8):1231-51. doi:10.1093/neuonc/noab106 - Pubmed