Examens cytologique, histologique, immunohistochimique et génétique des tumeurs du système nerveux central

Pathological examination of tumours of the central nervous system (CNS) is essential in terms of patient management. This examination is based on cytology, histology of fixed and paraffin-embedded specimens, and also on ancillary techniques such as immunohistochemistry and electron microscopy. Peroperative examination of biopsies is usually required to assess the representativeness of the fragments. If enough material is available, a specimen of the tumour is snap-frozen in liquid nitrogen. WHO classification of brain tumours distinguishes primitive and secondary tumours. Among primitive CNS tumours, the most frequent are neuroepithelial tumours, especially gliomas. Histopathological criteria for diagnosis and grading are well defined though sometimes controversial, such as for gliomas. Recently, molecular biology described specific genetic alteration patterns related to malignancy, for example for gliomas and meningiomas. Such data are added to pathological diagnosis.