Fig. 1: Radiological and histological features of a 30-year-old glioneuronal tumor (GNT) case.

a Magnetic resonance images show multi-cystic mass in left parietal lobe with peritumoral edema. Scanty enhancement is observed in the solid portion of the mass. No calcification is identified in the computed tomography. b The tumor shows well-developed blood vessels with perivascular hyalinization with sheet of tumor cells between the blood vessels (H&E bar: 200 μm). Atypical hyperchromatic or multiple nuclei are observed, which are possibly degenerative atypia produced by long-standing slow growing nature of the tumor (H&E bar: 100 μm). Immunohistochemical studies reveal positive tumor cell nuclei for NeuN antibody (bar 200 μm), diffuse strong positivity in tumor cells for synaptophysin (bar 200 μm), focal positivity for Olig2 (bar: 100 μm), focal positivity for GFAP (100 μm), diffuse positivity for c-MET (bar: 100 μm), and low Ki67 labeling index of 0.4% (bar: 100 μm).