A relatively slow-growing glioma that is derived from oligodendrocytes and tends to occur in the cerebral hemispheres, thalamus, or lateral ventricle. They may present at any age, but are most frequent in the third to fifth decades, with an earlier incidence peak in the first decade. Histologically, these tumors are encapsulated, relatively avascular, and tend to form cysts and microcalcifications. Neoplastic cells tend to have small round nuclei surrounded by unstained nuclei. The tumors may vary from well-differentiated to highly anaplastic forms. (From DeVita et al., Cancer: Principles and Practice of Oncology, 5th ed, p2052; Adams et al., Principles of Neurology, 6th ed, p655)

Oligodendroglioma is a type of diffusely infiltrating glioma and constitutes approximately 5% of primary intracranial tumors. They often involve the cortical gray matter and are most commonly seen in the frontal lobes. OGs are generally low grade WHO grade II neoplasms that are slow-growing tumors and have a favorable treatment response when compared to other gliomas. Grade III anaplastic OG is a more malignant form of the tumor which portends a less favorable prognosis and may occur de novo or as degeneration from the lower grade OG.

(oligodendroglioma, not otherwise specified) An oligodendroglioma in which there is insufficient information on the IDH genes and 1p/19q codeletion status.

Oligodendrogliomas (ODs) are primary glial brain tumors that are divided into grade II and anaplastic grade III tumors (World Health Organization [WHO] criteria). Typically, they have an indolent course, and patients may survive for many years after symptom onset.

Oligodendrogliomas are brain tumors arising from oligodendrocytes, a type of cell that makes up the supportive (glial) tissue of the brain. They can be low-grade (grade II) or high-grade (grade III, also called anaplastic). While they can be found anywhere within the cerebral hemisphere, they are most common in the frontal and temporal...