Oligodendroglioma (ODG) is a relatively rare glioma, also quite a demarcated tumor. Moreover, “pure” ODGs are even more rare; mostly mixed gliomas are observed (oligoastrocytomas). The tumor develops from a specific type of glial cells—oligodendrocytes—and accounts for 2–10% of all primary intracranial tumors and 5–25% of gliomas. Most of ODGs are slow-growing, benign, non-encapsulated infiltrative tumors of the white matter, which are usually located paraventricularly. 85% of tumors are supratentorial, affecting mostly the frontal lobe. The tumor is characterized by the formation of foci of cystic degeneration and calcifications. Malignization of ODGs manifests by cellular atypia, occurrence of mitoses in the tumor, and proliferation of vascular endothelium (Fig. 29.1).

Oligodendroglioma is a most common intracranial tumor that calcifies, which is clearly seen on CT. The neoplasm has a mixed density. 75% of ODGs do not accumulate contrast agent. MRI identifies a tumor with mixed hypo- and isointensity in T1-weighted images and hyperintense foci in T2-weighted images (Fig. 29.2).