Diagnosis and pathogenesis of gliomas

Gliomas are the commonest groups of tumours arising in the central nervous system (CNS) in both children and adults. Their incidence in both age groups appears to be increasing, for reasons that are poorly understood. The biological behaviour of gliomas varies from slow-growing well-demarcated tumours that are curable by excision to malignant invasive tumours that are uniformly fatal. Pathology has a major role to play in the management of patients with gliomas by providing a histological diagnosis and tumour grade, which are of major prognostic significance. Molecular genetic studies have found loss of genetic material in many gliomas, with progressive losses identified with increasing tumour grade. In oligodendrogliomas, loss of heterozygosity on chromosomes 1p and 19q is of therapeutic significance as a predictor of tumour response to chemotherapy. The forthcoming revision of the WHO classification of CNS tumours is expected to provide updated recommendations on glioma diagnosis and grading.