Multinodular and vacuolating neuronal tumour: emphasis on expression of early and late neuronal immunomarkers.

Aim: To analyse the expression of early, intermediate and late neuronal immunomarkers in multinodular and vacuolating neuronal tumour (MVNT) and understand the histogenesis of this rare tumour.

Materials And Methods: This is a retrospective study over a period of 5 years and included seven cases. Demographic, radiological and histopathological features were assessed. Immunohistochemistry was done for early (OLIG2, MAP2, Doublecortin), intermediate (alpha-internexin, neurofilament) and late neuronal immunomarkers (NeuN, synaptophysin).

Results: All tumours were located in the cerebral hemisphere, mostly confined to temporal lobes with long-standing seizure as the most common symptom. On Magnetic resonance imaging (MRI), these tumours appeared mostly solid and were hypointense on T1 weighted image, hypointense to hyperintense on T2 weighted image. Six out of the seven cases showed nodular as well as diffuse growth pattern, located within deep cortical and superficial subcortical white matter. The nodules were composed of intermediate to large neuronal cells with prominent nucleoli and cytoplasmic vacuolation. The vacuolated neuronal cells showed immunolabelling for early neuronal immunomarkers and an autophagic immunomarker p62. The expression of late and intermediate neuronal immunomarkers was variable to absent. CD34 positive ramified neural elements were observed in the adjoining cortex of six cases. Follow-up data for four cases showed indolent behaviour.

Conclusion: MVNT tumour cells consistently express early neuronal immunomarkers with variable expression of intermediate and late, suggesting maturation arrest early in the development. A combination of neuronal immunomarkers may be useful to diagnose these tumours when the classical histopathological pattern is not present.