Glioneuronal tumours are a group of primary brain neoplasms of relatively recent acquisition in the World Health Organization (WHO) Classification of the Central Nervous System tumours. In diagnostic practice it is still possible to encounter glioneuronal tumours that cannot be placed into any of the well-defined WHO categories despite a growing list of entities. We have recently published four paediatric cases of diffuse leptomeningeal tumours that cannot be easily classified in the currently used CNS WHO classification, but which have histological and immunohistochemical criteria to be considered as glioneuronal tumours. The clinical, neuroradiological and pathological long-term follow-up of an unusual diffuse leptomeningeal glioneuronal tumour is presented herein.