Multinodular and Vacuolating Tumour is a benign and indolent lesion predominantly involving the subcortical and deep white matter of the cerebral hemispheres and is characterised by multiple small nodular non-enhancing lesions with T2/FLAIR hyperintensity.
Description
Multi Nodular and Vacuolating Tumour (MNVT) is a benign and indolent lesion predominantly involving the subcortical and deep white matter of the cerebral hemispheres. The lesions are characteristically multiple, small and nodular, and despite their name, it is not currently considered neoplastic. Its behaviour is generally indolent, and it rarely progresses or causes significant symptoms, however 30% of adults may experience long-term seizures. They are considered do not touch lesions if not associated with intractable epilepsy.
Pathogenesis
The exact pathogenesis of MNVT is not known, as the nature of these lesions is still under investigation. However, it is believed that they may result from an aberration in normal neuronal migration or cortical organisation.
Subtypes
There are no known subtypes of MNVT.
Epidemiology, Risk Factors & Associations
- More commonly identified in adults, with a female predominance.
- There are no known risk factors or associations.
Clinical Features
Most individuals with MNVT are asymptomatic, and the lesions are often incidental findings on imaging. If symptoms occur, they may include mild seizures or headaches.
Complications
- There is no evidence of malignant transformation in MNVT.
- There is also no evidence of metastasis or progression of the disease.
Pathological Features
Histopathology
- Benign, mixed glial neuronal lesion consisting of nodules of disorganised neuronal cells located near the subcortical white matter
Serology
No specific serological markers have been associated with MNVT.
Biochemistry
No specific biochemical markers have been associated with MNVT.
Radiological Features
General Features
- Lesions are multiple, small, and nodular.
- Primarily involve the subcortical and deep white matter of the cerebral hemispheres.
- No post-contrast enhancement is observed.
CT
Not typically performed for these lesions.
MRI
- T2/FLAIR: Cluster of well-delineated, variable-sized hyperintense cysts within the subcortical white matter.
- DWI/ADC: No restriction of diffusion.
- T1 Gad+: No enhancement.
US
Not applicable for these intracranial lesions.
NM
- PET FDG: Not typically used for MNVT.
Grading and Staging
There is no specific grading or staging system for MNVT.
Diagnosis
The diagnosis of MNVT is typically made based on its characteristic appearance on MRI, with multiple small nodular lesions with T2/FLAIR hyperintensity and no post-contrast enhancement.
Differential Diagnosis
- Dysembryoplastic Neuroepithelial Tumours (DNET): Also benign WHO grade 1 slow-growing glioneuronal tumour with a multicystic bubbly appearance, however, they typically arise from cortical or deep white matter (vs. subcortical white matter).
- Multiple Sclerosis: White matter lesions would typically demonstrate enhancement and involve periventricular white matter, corpus callosum, brain stem, cerebellum and spinal cord.
- Metastatic disease: Typically shows enhancement and more aggressive behaviour (diffusion restriction, haemorrhage, perilesional oedema).
Management
Given the benign and indolent nature of MNVT, no specific treatment is generally required. Regular follow-up with imaging may be recommended to monitor for any changes in the lesions.