Imagerie des tumeurs cérébrales de l'enfant

Brain tumours are the leading cause of death related to cancer in children. Diagnosis is difficult due to the non-specific nature of symptoms. An initial imaging study includes a nonenhanced CT followed by contrast-enhanced MRI. The tumours are located, with increasing frequency, to the posterior fossa, midline and cerebral hemispheres. Posterior fossa tumours represent 60% of all brain tumours in children and surgical resection is the main prognostic factor, complemented in some cases by radiation and chemotherapy. These tumours can be divided according to histology and location as: (1) cerebellar pilocytic astrocytomas, (2) medulloblastoma, (3) ependymomas and (4) brain stem tumours. Midline tumours are composed of three groups: (1) craniopharyngiomas, in the sellar and hypothalamic regions; (2) germinomas, in the pineal and pituitary regions; and (3) optical tract gliomas, usually involving the optical chiasma. Their surgical removal is complicated by the risk of hypothalamic injury. Hemispheric tumours vary from benign lesions (e.g., dysembryoplastic neuroepithelial tumours [DNET]) to highly malignant tumours (e.g., glioblastomas [GBM]).