The presence of necrosis and/or microvascular proliferation does not influence survival of patients with anaplastic oligodendroglial tumours: review of 98 patients.

Accurate prognosis for patients with anaplastic oligodendroglial gliomas is increasingly difficult to make. Characterisation of these tumours remains challenging, increasing proportions of oligodendroglial diagnoses in gliomas are reported, and no WHO 2000 grade IV exists for them, so that highly anaplastic tumours can only be grouped with glioblastoma (GBM) or with grade III oligodendroglioma, which have differing clinical behaviour. Longer survival times reported for patients with glioblastoma containing an oligodendroglial element (GBMO) suggest that a grade IV for oligodendroglial tumours might exist.