THE NEW WHO CLASSIFICATION OF BRAIN-TUMOR S - RADIOLOGICAL ASPECTS OF4 NEW TUMOR ENTITIES

Purpose: Characterisation of the classification of brain tumours autho rised by the WHO. Method of appraisal: This classification was revised and published in its second version. In the revision, some tumours we re regrouped histogenetically and some tumour variants were added. Rad iologically relevant changes of the classification include the differe ntiation of four new tumour entities that are easily distinguished by MR imaging. These four tumours belong to the group of childhood tumour s or tumours occurring in early adulthood and are characterized by a g ood prognosis after extirpation. Results of appraisal: Central neurocy tomas are small-cyst ventricular tumours associated with the foramen o f Monroi and show moderate contrast enhancement. Infantile desmoplasti c gangliogliomas/astrocytomas commonly consist of a solid tumour porti on related to the leptomeninges with pronounced contrast enhancement a nd a typically very large cyst. Pleomorphic xanthoastrocytomas are cir cumscribed cortical tumours and usually show very moderate gyriform en hancement with only slight signs of a mass effect. Dysembryoblastic ne uroepithelial tumours, which originate in the cortical/subcortical reg ion, likewise show no mass effect; they are characterised by thickenin g of the cortex from surrounding dysplastic tissue and erosion of the calotte.