To review the current state of the classification and oncogenesis of
gliomas, emphasizing those biologic parameters with special clinical
significance. DEVELOPMENT: In the current classification, both histologic grade
and phenotype are considered the pathological features with more relevant
clinical impact. These factors are an obligatory reference for both all molecular
studies and a new classification. The relationship between the oligodendroglial
phenotype and the loss of chromosomes 1p and 19q is a useful data in the
histopathologic differential diagnosis. The new pathologic-molecular
classification should take into account the current state of knowledge about the
malignization pathways of gliomas, which have prognostic significance. The
neoplastic biological potential should be determined in each case according with
the tumoral heterogeneity. Then, this evaluation can be based on tumoral
microdissection. Although no well established prognostic molecular profiles are
available, several molecular alterations are relevant such as chromosome 10
deletion, especially of the 10q23 region, mutation of PTEN and TP53 genes and
amplification or mutation of EGFR. For treatment purposes, the combined deletion
1p/19q identifies the anaplastic type of oligodendrogliomas that are more
responsive to chemotherapy. CONCLUSIONS: The new pathomolecular classification of
gliomas should improve the old one, especially being concerned about the
oncogenesis and heterogeneity of these tumors. It is desirable that this
classification has clinical applicability and can integrate new molecular
findings with some known histological features with prognostic value
