European clinical practice recommendations for the diagnosis and treatment of paediatric pineal tumours

Paediatric tumours of the pineal region are rare CNS tumours accounting for 3% of brain tumours in children and adolescents; the majority of which are germ cell tumours. This review focuses on pineal parenchymal tumours (pineoblastoma, pineal parenchymal tumour of intermediate differentiation, pineocytoma) and those specifically arising in the pineal region (papillary tumours of the pineal region, desmoplastic myxoid tumour of the pineal region, SMARCB1-mutant and pineal cyst), which together account for up to a third of pineal tumours. In recent years, the diagnostic classification of these specific tumour-types has been refined by the integration of molecular pathology. Given the differences in grade, tumour biology and clinical behaviour, an accurate integrated neuropathological diagnosis is essential in deciding an appropriate treatment strategy which can range from surgery only to intensive multi-modal therapies. The most common of these tumours in children is WHO Grade 4 pineoblastoma, where specific molecular subgroups occurring in very young patients are difficult to treat successfully. Further challenges include the anatomical position and associated surgical risk together with a lack of molecularly annotated clinical data and consequent limited evidence to guide the therapeutic approach due to their rarity. These guidelines aim to provide a framework for diagnosis, prognostication and management based on current literature and expert opinion.