ACR Codes: 1.3
Oligodendroglioma accounts for approximately 5% of intracranial gliomas, although mixed tumors with astrocytic components are increasingly being recognized. These commonly present in adults as densely calcified cortical or subcortical masses of the frontal or temporal lobes. Less common locations include the deep cerebral white matter, and rarely the cerebellum or spinal cord. Foci of central necrosis and cyst formation are common in larger lesions. Spontaneous hemorrhage is well known and may be catastrophic. Calcifications are associated with blood vessels and may progress to frank lamellar bone formation. Oligodendroglioma is rare in children, tending to present in adolescent males. Although these masses often present with a prolonged history of vague neurologic deficits or seizure disorder, unpredictable rapid progression from time of diagnosis due to malignant transformation is not unusual. Leptomeningeal dissemination may occur, but remote metastases are very rare. Surgical resection and radiation therapy are the usual treatment modalities.
On MR, oligodendroglioma is nonspecifically hypointense on T1-weighted and hyperintense on T2-weighted images. Calcifications tend to be underestimated or inapparent. Occasionally, foci of increased signal on T1-weighted images reflect intratumoral hemorrhage. Enhancement on CT or MR is variable, with edema recognizable on CT in about 30%. On CT, calcifications are expected and may be shell-like, ring-like, or nodular. Up to 40% result in recognizable calcifications on plain skull films.
The differential diagnosis in adults primarily includes other gliomas, particularly astrocytoma. In children, astrocytoma, ganglioglioma/gangliocytoma, neuroblastoma, or other primitive neuroectodermal tumors (PNET) could have a similar radiographic appearance.
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Disease Topic 1429 
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