Pathological classification of brain tumors.

The tumors of the central nervous system are classified according to the last international classification published by World Health Organization. The Classification of Tumors of the Central Nervous System was done on 2007, based on morphological features, growth pattern and molecular profile of neoplastic cells, defining malignancy grade. The neuropathological diagnosis and the grading of each histotype are based on identification of histopathological criteria and immunohistochemical data. The histopathology, also consisting of findings with prognostic or predictive relevance, plays a critical role in the diagnosis and treatment of brain tumors. The recent progresses on radiological, pathological, immunohistochemical, molecular and genetic diagnosis improved the characterization of brain tumors. Molecular and genetic profiles may identify different tumor subtypes varying in biological and clinical behavior. To investigate new therapeutic approaches is important to study the molecular pathways that lead the processes of proliferation, invasion, angiogenesis, anaplastic transformation. Different molecular biomarkers were identified by genetic studies and some of these are used in neuro-oncology for the evaluation of glioma patients, in particular combined deletions of the chromosome arms 1p and 19q in oligodendroglial tumors, methylation status of the O-6 methylguanine- DNA methyltransferase gene promoter and alterations in the epidermal growth factor receptor pathway in adult malignant gliomas, isocitrate dehydrogenase 1 (IDH1) and IDH2 gene mutations in diffuse gliomas, as well as BRAF status in pilocytic astrocytomas. The prognostic evaluation and the therapeutic strategies for patients depend on synthesis of clinical, pathological and biological data: histological diagnosis, malignancy grade, gene-molecular profile, radiological pictures, surgical resection and clinical findings (age, tumor location, "performance status").