Multinodular and Vacuolating Posterior Fossa Lesions of Unknown Significance

Abstract

Multinodular and vacuolating neuronal tumor of the cerebrum is a rare supratentorial brain tumor described for the first time in 2013. Here, we report 11 cases of infratentorial lesions showing similar striking imaging features consisting of a cluster of low T1-weighted imaging and high T2-FLAIR signal intensity nodules, which we referred to as multinodular and vacuolating posterior fossa lesions of unknown significance. No relationship was found between the location of the lesion and clinical symptoms. A T2-FLAIR hypointense central dot sign was present in images of 9/11 (82%) patients. Cortical involvement was present in 2/11 (18%) of patients. Only 1 nodule of 1 multinodular and vacuolating posterior fossa lesion of unknown significance showed enhancement on postcontrast T1WI. DWI, SWI, MRS, and PWI showed no malignant pattern. Lesions did not change in size or signal during a median follow-up of 3 years, suggesting that multinodular and vacuolating posterior fossa lesions of unknown significance are benign malformative lesions that do not require surgical intervention or removal. ABBREVIATIONS: IQR interquartile range; MVNT ¼ multinodular and vacuolating neuronal tumor of the cerebrum; MV-PLUS ¼ multinodular and vacuolating posterior fossa lesions of unknown significance M ultinodular and vacuolating neuronal tumor of the cerebrum (MVNT) is a rare brain tumor described for the first time in 2013 and added in the World Health Organization Classification of Tumors of the Central Nervous System in 2016. 1,2 Its prevalence and pathophysiology are unknown. It is often asymptomatic and discovered incidentally. It remains unclear whether MVNT should be considered a true neoplasm or a malformative lesion. 1-7 MVNTs have been reported to show highly suggestive imaging features, especially with MR imaging. 8-16 MVNT consists of the coalescence of small T2-weighted imaging and T2-FLAIR

A rare cause of adult's epileptic crisis: Infratentorial multinodular and vacuolating neuronal tumor

“…found lesions that partially or totally cancel on the T2 Flair sequence. Most studies suggest that these lesions do not show enhancement after contrast injection or diffusion restriction, which is consistent with our case [6] .…”

“…Very few data concerning perfusion are found in literature. We note, however, a decrease in perfusion in some cases [6] . Finally, the unchanging nature of these lesions over time is also an important diagnostic criterion to take into account.…”

The 2021 WHO Classification for Gliomas and Implications on Imaging Diagnosis: Part 3—Summary of Imaging Findings on Glioneuronal and Neuronal Tumors

“…79 Recently, remarkably similar imaging findings have been reported in the posterior fossa, but as tissue confirmation was not performed in these patients, caution should be taken in diagnosing patients as MVNT in the posterior fossa. 80 A representative case is shown in Fig. Dysplastic cerebellar gangliocytoma is usually located in the unilateral cerebellum.…”

Advanced multiparametric magnetic resonance imaging of multinodular and vacuolating neuronal tumor

“…Multinodular and vacuolating neuronal tumors have been reported to display highly suggestive imaging features, especially on magnetic resonance imaging (MRI) [3‐13]. An MVNT consists of the coalescence of small T2‐weighted imaging and fluid‐attenuated inversion recovery (FLAIR) hyperintense nodules in subcortical and juxtacortical areas, with rare or no post‐contrast enhancement.…”