Grading of gliomas.

The traditional schemes for grading gliomas, in particular astrocytomas, have not been widely accepted by the neuropathology community. At present, four systems are in use, separating either three or four grades of tumour. All four systems are histopathology-based. Intermediate grade astrocytomas show a wide variation in survival times and prediction based on histopathological features remains problematic. Molecular-genetic alterations that have been identified in astrocytomas will eventually be incorporated into grading schemes as indicators of where a tumour has reached in the biological continuum from low to high grade of malignancy.