Multinodular and vacuolating neuronal tumours
Multinodular and vacuolating neuronal tumours (MVNT) have only recently been described and have only been recognised in the 2016 revision of the WHO classification of CNS tumours,
The are small 'bubbly' appearing indolent subcortical tumours that sometimes present with seizures. These tumours 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.
The true epidemiology of these tumours is unknown as they have only been recently described and many are asymptomatic and thus likely undiagnosed (or misdiagnosed). Reported cases are mostly in young to middle aged individuals with adult onset epilepsy 1.
Many of these lesions are probably asymptomatic and may be found incidentally on imaging for other reasons, and have, over the year, been misinterpreted a variety of other lesions (see differential diagnosis below). In some individuals these tumours are epileptogenic.
Macroscopically these tumours appear as a cluster of small well circumscribed nodules. They are located in the subcortical white matter and adjacent deep cortex 1-3.
Microscopically they are composed of mature-appearing neurons embedded within a fibrillary background, with large cytoplasmic vacuoles 1.
Immunostaining is positive for synaptophysin,HuC/HuD neuronal antigens
and p62 but were negative for other markers (e.g. IDH1, nestin, NeuN, neurofilament, GFAP and CD34) 1-3.
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 tumours appear as a cluster of well circumscribed high T2 signal 'bubbles' located predominantly in the subcortical white matter, but can involve overlying cortex 1,3.
- T1: hypointense to adjacent grey and white matter
- usually no enhancement
- some faint focal enhancement may be seen 3
- T2: hyperintense to grey and white matter, almost as high as CSF
- FLAIR: do not suppress
Treatment and prognosis
MVNTs appear to be benign tumours with very indolent biological behaviour which can, if asymptomatic, be followed with imaging alone. In symptomatic patients (epileptic) surgical resection often controls seizures, with no tumour regrowth reported 1-3.
dysembryoplastic-neuroepithelial-tumour - DNET
- 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 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
- 1. Bodi I, Curran O, Selway R et-al. Two cases of multinodular and vacuolating neuronal tumour. Acta Neuropathol Commun. 2014;2 (1): 7. doi:10.1186/2051-5960-2-7 - Free text at pubmed - Pubmed citation
- 2. Fukushima S, Yoshida A, Narita Y et-al. Multinodular and vacuolating neuronal tumor of the cerebrum. Brain Tumor Pathol. 2015;32 (2): 131-6. doi:10.1007/s10014-014-0198-9 - Pubmed citation
- 3. Huse JT, Edgar M, Halliday J et-al. Multinodular and vacuolating neuronal tumors of the cerebrum: 10 cases of a distinctive seizure-associated lesion. Brain Pathol. 2013;23 (5): 515-24. doi:10.1111/bpa.12035 - Pubmed citation