Core Terms & Classification

Oligodendroglioma (overview)

An oligodendroglioma is a glioma defined by an IDH mutation together with 1p/19q codeletion, generally carrying the most favorable outlook among adult diffuse gliomas.

In short: Oligodendroglioma (overview)

It is defined by IDH mutation plus 1p/19q codeletion.
Both features are required for the diagnosis.
It generally has the most favorable outlook among adult diffuse gliomas.
It is graded 2 or 3.

What it is

An oligodendroglioma is a glioma defined, in the modern classification, by two molecular features together: an IDH mutation and 1p/19q codeletion (loss of parts of chromosomes 1 and 19). It generally carries the most favorable outlook among the adult diffuse gliomas.

Understanding Oligodendroglioma (overview)

Historically named for cells resembling oligodendrocytes, oligodendroglioma is now defined molecularly: a diffuse glioma must have both an IDH mutation and 1p/19q codeletion to be classified as an oligodendroglioma. This combination is associated with a relatively favorable outlook and with particular sensitivity to certain chemotherapy (such as PCV). Oligodendrogliomas are graded 2 or 3 (there is no grade 4 oligodendroglioma in the current system). They tend to grow more slowly and respond better to treatment than astrocytomas and, especially, glioblastoma — though they are still serious tumors requiring careful management. The requirement for both molecular features means molecular testing is essential to confirm the diagnosis. Understanding oligodendroglioma clarifies a molecularly defined glioma with a comparatively favorable outlook.

Why it matters

Understanding oligodendroglioma helps patients and families see that this molecularly defined glioma (IDH-mutant and 1p/19q-codeleted) generally carries the most favorable outlook among adult diffuse gliomas — though it still requires careful management.

Common questions

What defines an oligodendroglioma?

An IDH mutation together with 1p/19q codeletion.

Are both features needed?

Yes — both are required for the diagnosis.

Is the outlook favorable?

It is generally the most favorable among adult diffuse gliomas.

Bottom line

An oligodendroglioma is defined by IDH mutation plus 1p/19q codeletion, generally carrying the most favorable outlook among adult diffuse gliomas, and is graded 2 or 3.

More terms in Core Terms & Classification

Glioblastoma (overview)Glioblastoma is the most aggressive and most common malignant primary brain tumor in adults, now defined as an IDH-wildtype, grade 4 diffuse astrocytic glioma.
Ependymoma (overview)An ependymoma is a glioma arising from ependymal cells lining the brain's fluid spaces, a distinct type from the diffuse gliomas, often more circumscribed.
GliomaA glioma is a tumor that arises from the glial cells of the brain or spinal cord, the most common type of primary brain tumor.
Brain tumorA brain tumor is an abnormal growth of cells in or around the brain, which may be benign or malignant and may begin in the brain or spread from elsewhere.
Primary brain tumorA primary brain tumor is one that begins in the brain itself, as opposed to spreading there from cancer elsewhere; gliomas are primary brain tumors.

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