Description:
Oligodendroglioma is a rare, slow-growing primary brain tumor arising from oligodendrocytes, a type of glial cell. It is classified as a diffuse glioma and is characterized by IDH mutations and 1p/19q co-deletion, which are diagnostic and prognostic markers.
Key Features:
Classification:
– WHO Grade II (low-grade) or Grade III (anaplastic oligodendroglioma, more aggressive).
– Defined by IDH mutation + 1p/19q co-deletion (essential for diagnosis).
– Age Group:
– Most common in adults (30–50 years).
– Symptoms:
– Seizures (most common presenting symptom).
– Headaches, cognitive changes, focal neurological deficits.
– Histopathology:
– “Fried egg” appearance (round nuclei with clear cytoplasm).
– Microcalcifications and branching capillaries (“chicken-wire” pattern).
– Molecular Markers:
– 1p/19q co-deletion (diagnostic).
– TERT promoter mutations (associated with better prognosis).
Treatment:
1. First-Line:
– Maximal safe surgical resection (goal is gross total resection).
– Adjuvant therapy (if high-risk or anaplastic):
– PCV chemotherapy (Procarbazine + CCNU + Vincristine).
– Radiation therapy** (for Grade III or symptomatic progression).
2. Targeted/Investigational Therapies:
– IDH inhibitors (e.g., vorasidenib for recurrent low-grade gliomas).
– Immunotherapy trials (limited efficacy due to low mutational burden).
Prognosis:
– Grade II: Median survival 10–15 years.
– Grade III (Anaplastic): Median survival 6–10 years.
– 1p/19q co-deletion predicts better response to chemotherapy and longer survival.
Diagnosis:
– MRI: Typically shows a T2/FLAIR hyperintense, non-enhancing mass (unless anaplastic).
– Biopsy + Molecular Testing: Required for IDH and 1p/19q status.
Conclusion:
Oligodendroglioma is a molecularly defined glioma with a relatively favorable prognosis compared to other gliomas. Surgery followed by PCV chemo ± radiation is standard for high-risk cases, while observation may be appropriate for asymptomatic low-grade tumors. Ongoing research focuses on IDH-targeted therapies to improve outcomes.