Multinodular and vacuolating neuronal tumor: Case report of a rare pathologic diagnosis

Abstract Multinodular and vacuolating neuronal tumor (MVNT) is a unique lesion first characterized in 2013. We report a case of MVNT in a 34-year-old male with a longstanding history of mood instability who presented after new onset seizure-like activity characterized by auditory and visual hallucinations. Magnetic resonance imaging (MRI) of the brain showed a non-enhancing, T2 hyperintense mass in the right anterior temporal lobe. The patient underwent right frontotemporal craniotomy, anterior temporal lobectomy, and amygdalohippocampectomy for resection of the tumor. Microscopic sections of the mass demonstrated lower cortical/subcortical nodular aggregates of “neuronal-type” tumor cells with eosinophilic and multivacuolated cytoplasm. The tumor cells diffusely infiltrated the hippocampus, but the normal neurons of the dentate gyrus and cornu ammonis remained intact. Synaptophysin and neurofilament protein immunostains confirmed the neuronal phenotype of the tumor cells