Core Terms & Classification
Adult-type diffuse glioma
Adult-type diffuse gliomas are the main group of infiltrating gliomas in adults, comprising IDH-mutant astrocytoma, IDH-mutant oligodendroglioma, and IDH-wildtype glioblastoma.
In short: Adult-type diffuse glioma
- They are the main infiltrating gliomas in adults.
- They comprise three molecular groups.
- The groups are IDH-mutant astrocytoma, IDH-mutant oligodendroglioma, and glioblastoma.
- They are defined primarily by IDH status and 1p/19q codeletion.
What it is
Adult-type diffuse gliomas are the principal group of infiltrating (diffuse) gliomas occurring in adults. Under the modern WHO classification, they comprise three molecularly defined types: astrocytoma (IDH-mutant), oligodendroglioma (IDH-mutant and 1p/19q-codeleted), and glioblastoma (IDH-wildtype).
Understanding Adult-type diffuse glioma
The WHO CNS5 classification simplified the adult diffuse glioma category into these three groups, defined primarily by two molecular features: whether the tumor has an IDH mutation, and (in IDH-mutant tumors) whether it has 1p/19q codeletion. An IDH-mutant tumor without 1p/19q codeletion is an astrocytoma; an IDH-mutant tumor with 1p/19q codeletion is an oligodendroglioma; and an IDH-wildtype diffuse astrocytic tumor (with certain features) is a glioblastoma. This grouping reflects biology and is highly relevant to prognosis and treatment — for example, oligodendrogliomas generally have the most favorable outlook, and IDH-mutant tumors generally do better than IDH-wildtype glioblastoma. "Adult-type" distinguishes these from "pediatric-type" diffuse gliomas, which have different biology. Understanding adult-type diffuse gliomas clarifies the central framework for the most common adult gliomas.
Why it matters
Understanding adult-type diffuse gliomas helps patients and families see the central framework for adult gliomas — three molecular groups whose distinctions (IDH status, 1p/19q codeletion) strongly shape prognosis and treatment.
Common questions
What are adult-type diffuse gliomas?
The main infiltrating gliomas in adults.
What three types do they include?
IDH-mutant astrocytoma, IDH-mutant oligodendroglioma, and IDH-wildtype glioblastoma.
What defines them?
Primarily IDH status and 1p/19q codeletion.
Bottom line
Adult-type diffuse gliomas are the main adult infiltrating gliomas — IDH-mutant astrocytoma, IDH-mutant oligodendroglioma, and IDH-wildtype glioblastoma — defined by molecular features.
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