What Is Oligodendroglioma?
Oligodendroglioma is a primary central nervous system (CNS) tumor involving the brain and spinal cord. They are most frequently observed in the frontal lobes and affect the cortical gray tissue. Approximately five percent of initial intracranial tumors are oligodendrogliomas.
How Do Oligodendrogliomas Develop?
Bailey and Bucy gave oligodendrogliomas their original name in 1929 as they resembled a type of cell found in the central nervous system (oligodendrocytes). Oligodendrocytes are brain cells that nourish and insulate nerve fibers of the central nervous system. Oligodendrogliomas are found in the white matter and the cortex, the brain's outer layer. The tumors appear to develop from neural progenitor (type of brain cells) cells with glial (brain cells) precursors and resemble oligodendrocytes.
Why Do Oligodendrogliomas Develop?
Cancer is a genetic disease; specific mutations to the genes that regulate cells cause this disease. Mutations of the genes cause an increase in cancer cells. An increased risk of developing oligodendrogliomas relates to radiation exposure or specific gene mutations in family history.
What Is the Incidence of Oligodendrogliomas?
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Although they can happen at any age, oligodendrogliomas most frequently affect adults between the ages of 35 and 44.
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Males are more likely to develop oligodendrogliomas than females.
What Are the Grades of Oligodendroglioma?
The primary tumors of the central nervous system are categorized according to the patient's age and the type, size, and extent of cancer. The characteristics of oligodendrogliomas divide them into two classes:
1. Grade II-
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They are low-grade tumors that develop slowly and infiltrate surrounding healthy tissue.
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They frequently develop years before being recognized since there are no symptoms.
2. Grade III-
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They are malignant Grade III oligodendrogliomas.
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Therefore, they rapidly expand and spread to other body parts.
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They are also known as anaplastic oligodendrogliomas.
How Is an Oligodendroglioma Diagnosed?
1. Biopsy-
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A biopsy on a small tissue removed during surgery ensures an accurate diagnosis.
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A neuropathologist would provide a precise analysis of the tumor tissue.
2. Magnetic Resonance Imaging-
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Oligodendrogliomas present as a single tumor with distinct borders and considerable swelling surrounding the cancer.
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Anaplastic oligodendrogliomas are the most common type.
Which Tissues Do the Oligodendrogliomas Invade?
Oligodendrogliomas can spread throughout the central nervous system through cerebrospinal fluid (CSF). Rarely do oligodendrogliomas spread to other organs outside the central nervous system.
What Signs and Symptoms Are Present in Oligodendroglioma?
Depending on the tumor's location, the symptoms of oligodendroglioma may vary. These signs and symptoms might manifest as
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Headaches.
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Issues with memory and thought.
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Weakness.
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Numbness.
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Imbalance and mobility issues.
What Is the Prognosis of Oligodendrogliomas?
Oligodendroglioma has a relative five-year survival rate of 74.1 %; the prognosis can be affected by various circumstances. Practitioners must inform this cancer's characteristics according to the patient's age and health and advise suitable therapy.
What Is the Differential Diagnosis for Oligodendroglioma?
1. Astrocytoma-
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The primary differential diagnosis based on imaging is a diffuse astrocytoma, essentially identical to oligodendroglioma.
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On imaging, diffuse astrocytoma frequently has less dystrophic calcification, more white matter, and less cortical involvement than oligodendroglioma.
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However, they can be differentiated from oligodendroglioma by the absence of the 1p/19q deletion (type of chromosome alteration) in astrocytomas.
2. Glioblastoma-
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Glioblastoma is a crucial diagnostic factor of oligodendroglioma.
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They often have restricted diffusion patches and central necrosis areas, rare in oligodendroglioma.
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Calcification is highly prevalent in oligodendroglioma but rare in glioblastoma.
3. Dysembryoplastic Neuroepithelial Tumors (DNET)-
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It is a low-grade subcortical neoplasm that resembles oligodendrogliomas.
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They tend to have a more bubbly cystic appearance and may have surrounding cortical dysplasia.
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Oligodendrogliomas are more frequently identified in older persons, whereas dysembryoplastic neuroepithelial tumors (DNET) are found in children and young adults.
4. Ganglioglioma-
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Another subcortical tumor that is more common in children and young adults and can cause seizures is ganglioglioma.
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On an MRI, gangliogliomas often appear as a cyst with an enhancing nodule and are more frequently found in the temporal lobe than in oligodendrogliomas.
5. Multinodular and Vacuolating Neuronal Tumor (MVNT)-
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A subcortical lesion commonly manifests as a collection of tiny bubbly cysts that do not usually enhance. They are discovered by chance and maybe a malformation or dysplastic lesion rather than an actual tumor.
What Are the Treatments Options for Oligodendroglioma?
1. Surgery-
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Surgery is the first line of defense against an oligodendroglioma.
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It aims to acquire tissue to identify the type of tumor and remove as much cancer as feasible without increasing the patient's symptoms.
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The type of surgery chosen is based on the tumor's location, the patient's age, or any potential risks.
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Resection is the preferred course of treatment.
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Repeat surgical resection is still recommended to cure patients with low-grade tumors that have been partially removed and show increased tumor growth over time or in patients at risk for developing higher-grade neoplasms.
2. Radiotherapy-
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After surgical resection, radiotherapy is frequently used to treat oligodendroglioma.
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Early postoperative radiotherapy has been associated with an improved time to progression and better seizure control after surgery.
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Hyperfractionated standard-focused or limited-field radiation therapy is frequently used.
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The dose delivered recommendations of 45-65 Gy in 1.8-2 Gy segments.
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Depending on the prognosis, dosage and timing are case-specific.
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Hypofractionated doses, which deliver single fractions for the same or lower total amount, may be used in older patients with a worse prognosis.
3. Chemotherapy-
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It is a frequently used adjunct with radiation therapy (RT) or alone.
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The use of Procarbazine, Lomustine, and Vincristine (PCV) are used in combination to treat oligodendroglioma.
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However, this regimen usually is only used for six cycles due to unfavorable side effects.
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Temozolomide (TMZ) is the treatment of choice to avoid adverse effects.
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Using novel chemotherapy, targeted therapy, or immunotherapy medications is also available.
Conclusion:
Oligodendroglioma is a diffuse infiltrating glioma that makes up around five percent of all primary cerebral tumors. The healthcare team chooses the patient's treatments based on the patient's age, the amount of tumor that remains after surgery, the type of tumor, and the location of the cancer. Although oligodendroglioma is a low-grade tumor, it can cause significant morbidity. Older persons in their fourth and fifth decades are most frequently affected by oligodendroglioma. Early detection and thorough surgical removal improve outcomes and have a considerably better prognosis.