What is Oligodendroglioma?
Oligodendroglioma is an uncommon, slow-growing brain tumor that develops from oligodendrocytes, the glial cells responsible for forming the myelin sheath in the central nervous system. Although it accounts for only 5–15% of all gliomas, it represents a clinically important entity because of its relatively favorable prognosis compared with other diffuse gliomas. Most cases occur in adults between 30 and 50 years of age, though it can appear at any age.
Causes of Oligodendroglioma
The causes of brain oligodendroglioma remain incompletely understood. However, significant progress has been made in molecular neuropathology:
Genetic alterations:
1p/19q codeletion: A hallmark genetic signature strongly associated with classic oligodendrogliomas. It predicts better response to chemotherapy and radiotherapy, leading to prolonged survival.
IDH1/IDH2 mutations: Found in the majority of oligodendrogliomas and linked to favorable prognosis.
Epigenetic factors: Methylation of MGMT promoter affects chemotherapy response.
Environmental exposures: Long-term exposure to ionizing radiation and rare hereditary cancer syndromes may increase risk, although data are limited.
Clinical Presentation
The symptoms of oligodendroglioma of brain depend on tumor location, size, and growth rate:
Seizures: The most common presentation, occurring in up to 80% of patients. Seizures may be focal or generalized.
Headaches: Due to increased intracranial pressure or mass effect.
Cognitive and personality changes: Common with frontal lobe involvement, manifesting as memory impairment, apathy, or mood disorders.
Focal neurological deficits: Speech disturbance, visual field loss, or hemiparesis, depending on the tumor site.
Progression to high-grade disease: Low-grade tumors may transform into anaplastic variants, leading to rapid worsening of symptoms.
Oligodendroglioma Radiology
Imaging plays a pivotal role in diagnosis. Oligodendroglioma MRI radiology features are distinctive but require correlation with pathology:
CT Scan: Calcifications are highly characteristic (seen in up to 90% of cases).
Appears as a cortical or subcortical hypodense mass.
MRI Oligodendroglioma: T1-weighted: Hypointense or isointense lesion.
T2/FLAIR: Hyperintense, often showing heterogeneous signal due to calcifications and cystic areas.
Contrast enhancement: Variable; usually mild or patchy in low-grade tumors, stronger in high-grade lesions.
Diffusion imaging: Helps differentiate tumor infiltration from edema.
MR spectroscopy: Elevated choline and reduced N-acetylaspartate, consistent with neoplasm.
Grading and Classification
Oligodendrogliomas are classified by the WHO based on histology and molecular profile:
Grade 2 (Low-Grade Oligodendroglioma)
Slow-growing, less aggressive.
Patients may live many years with stable disease after treatment.
Grade 3 (Oligodendroglioma Stage 3, Anaplastic Oligodendroglioma)
Faster growing and more aggressive.
Higher risk of recurrence and malignant progression.
Requires combined modality therapy (surgery + radiotherapy + chemotherapy).
Diagnostic Approaches
Neurological Examination: Detects focal neurological deficits (speech impairment, motor weakness, visual field loss).
Helps localize the lesion before imaging.
Radiological Imaging: CT and MRI provide critical anatomical details.
Functional MRI can identify eloquent cortex regions before surgery.
Histopathology: Tumor composed of round nuclei with a “fried-egg” appearance and delicate branching capillaries.
Molecular Testing: Essential for modern classification: confirmation of IDH mutation and 1p/19q codeletion distinguishes oligodendroglioma from other gliomas.
Oligodendroglioma Treatment
The management of oligodendroglioma brain tumors is multidisciplinary and individualized:
1.Microsurgical Resection
The first-line and most effective treatment.
Aim: Maximum safe removal without damaging critical brain areas.
Gross total resection improves seizure control and long-term survival.
2.Radiotherapy
Used postoperatively, especially for high-grade tumors or incomplete resections.
Fractionated radiotherapy reduces risk of recurrence.
3.Chemotherapy
Especially for high-grade tumors (Grade 3, Anaplastic Oligodendroglioma
Temozolomide (TMZ): Often used due to better tolerance, either alone or with radiotherapy.
PCV regimen (procarbazine, lomustine, vincristine): Especially in 1p/19q codeleted tumors.
4.Seizure Management
Antiepileptic drugs are essential for controlling seizures.
Surgery itself often improves seizure frequency.
5.Supportive Care (If necessary)
Rehabilitation for motor, speech, or cognitive deficits.
Psychological support and neurocognitive rehabilitation for long-term survivors.
The Role of Neuro-Oncology Tumor Boards
Neuro-oncology tumor boards bring together specialists from neurosurgery, medical oncology, neuroradiology, pathology and radiation therapy to discuss individual cases. These interdisciplinary meetings enhance treatment planning, foster personalized care, and have been linked to prolonged survival and better quality of life.
Conclusion
Oligodendroglioma of brain is a unique glial tumor characterized by specific genetic markers and relatively favorable outcomes compared with other gliomas. Accurate diagnosis requires a combination of clinical evaluation, imaging, histopathology, and molecular profiling. With advances in surgery, radiotherapy, and chemotherapy, patients are living longer and with better quality of life. Personalized treatment approaches and continuous follow-up remain the cornerstone of effective management.0