Histological grading of gliomas.

Usefulness of grading systems based on non-specific features (e.g. mitosis, necrosis) is unequivocal in only certain types of astrocytomas, and their efficiency remains to be seen in oligodendrogliomas and in mixed oligo-astrocytomas. The possibility of grading ependymomas is still uncertain. Accordingly, only a small proportion of gliomas which occur in children can be reliably graded. Lack of reproducibility is a severe impediment of both current conventional and kinetic methods in the prognosis of gliomas.