Oligoastrocytomas is a historical term no longer recognised in the WHO classification of CNS tumours previously to denote intracranial tumours that are part of the glial cell continuum, with mixed oligodendroglial and astrocytic cell populations based on histological features and typically occurred in young adults.
The literature is somewhat conflicted on these entities, with imaging appearance and incidence varying widely.
Epidemiology
Historically these tumours at some institutions had been encountered commonly, in some instances accounting for 50% of all oligodendrogliomas and considered the third most common glial neoplasm 2. At other sites they were rare. Due to the vague criteria for their definition and wide interobserver variability, however, it is not possible to infer a reliable incidence of oligoastrocytomas 6.
Pathology
The updated 4th edition (2016) to the WHO classification of CNS tumours required molecularly distinct populations of both components to be identified: astrocytic (IDH-mutant, ATRX-mutant, 1p19q-intact) and oligodendrocytic (IDH-mutant, ATRX-wildtype, 1p19q co-deleted) 8.
In the 5th edition (2021) the term oligoastrocytoma is no longer recognised as a distinct diagnosis 9.