Anaplastic oligodendroglioma NOS

Old term

A diffusely infiltrating anaplastic glioma with oligodendroglial histology without demonstration of IDH mutation and 1p/19q co-deletion. Stains for IDH mutation and nuclear positivity for ATRX support the diagnosis of an oligodendroglial tumor but cannot substitute for 1p/19q co-deletion.

The differential diagnosis of Glioblastoma (especially small-cell variant) may be more appropriate (especially when IDH mutations are absent and genetic features of Glioblastoma are detectable.

Treatment: see Treatment of WHO grade III & IV diffuse gliomas