AimsTo study three atypical glioneuronal tumours (GNTs), in order to shed light on the clinical and pathological features of this diverse tumour group. Methods and resultsClinical and neuropathological data for each case were retrospectively reviewed. Case 1 involved a 17-year-old boy with left leg movement difficulty. A mass lesion in the basal ganglia was detected radiologically; histopathological features included neurocytic/perivascular rosettes and a pilocytic astrocytoma component. Case 2 involved a 33-year-old man with intractable epilepsy. His left parietal lobe contained a cyst-like mass, resembling dysembryoplastic neuroepithelial tumour and rosette-forming glioneuronal tumour of the fourth ventricle microscopically. Case 3 involved a 21-year-old woman with a mass lesion in the mesencephalic tegmentum extending to the third and fourth ventricles and the suprasellar region. The lesion contained perivascular/neurocytic rosettes and an oligodendroglioma-like component. None of the tumours expressed an isocitrate dehydrogenase I mutation of the R132H type or contained a 1p/19q deletion, a BRAF(V600E) mutation, or KIAA1549-BRAF fusion. ConclusionsWe describe three GNTs with atypical histopathology and locations. Additional cases and molecular studies are needed to better understand the biological nature of GNTs and to refine their classification system.