NSRG-02. UNUSUAL DISSEMINATED DYSEMBRYOPLASTIC NEUROEPITHELIAL TUMOR INDICATING ROSETTE-FORMING GLIONEURAL TUMOR

Abstract

Dysembryoplastic neuroepithelial tumor (DNT) is usually a localized tumor in the temporal or frontal lobe, and dissemination or progression of DNT is very rare. Few reports have described multifocal DNTs. Here we present a case of disseminated, progressive tumor with DNT features. A 9-year-old boy was referred to our hospital with headache and epilepsy. MRI indicated left medial temporal tumor involving the cerebral cortex, which showed T1-weighted hypointensity and T2-weighted hyperintensity without gadolinium contrast enhancement. The tumor gradually enlarged, and initial surgery comprising partial resection was therefore performed at 10 years old. The initial pathological diagnosis was DNT. Disseminated lesions on the lateral ventricle walls were identified and the residual temporal lesion gradually enlarged. At 15 years old, the residual tumor involving the hippocampus and amygdala underwent subtotal removal. Histopathological findings from the second surgery mainly comprised specific glioneuronal elements indicating DNT. However, islands of high cellularity containing neurocytic rosettes were also observed. No pilocytic astrocytoma-like component was observed. No mitosis was detected. We finally diagnosed rosette-forming glioneural tumor (RGNT) with DNT background. Recently, some reports of mixed tumors comprising RGNT and DNT have been published. Those tumors often showed CSF dissemination. Tumors with DNT features and disseminated lesions may represent RGNT, and neurocytic rosette should be looked for in such cases.