Oligodendroglioma

Oligodendroglioma is type of glioma that develops from ologodendrocytes. It often occurs in frontal and temporal lobes and accounts for 2% of all brain tumor, 5% of intracranial tumors, and 10% of gliomas. 1  Oligodendroglioma is identified by its ‘box like’ or ‘fried egg’ appearance. 1  This type of tumor is more common in men and peaks between the age of 20 and 40. 1 || The cause for oligodendroglioma is unkown, but most tumors show abnormalities of chromosome 19 and 1. 1 ||
 * **Epidemiolgy:** || Amanuel
 * **Etiology:** || Amanuel
 * **Signs & Symptoms:** || Lindsey

Signs and symptoms for CNS tumors depend on tumor location, associated expansion and surrounding edema. 2 Tumor growth along with edema may cause focal neurologic dysfunction, increased intracranial pressure and/or hydrocephalus. With significant cerebral edema or hydrocephalus, nausea and vomiting, headache, and papilledema (swelling of the optic nerve caused by increased intracranial pressure) are common. Headaches may be worse in the morning and focal neurologic deficits are also common. Long term increased intracranial pressure may lead to optic atrophy and even blindness. Seizures are also common, usually with low grade neoplasms. Lumbar back pain, bowel or bladder dysfunction may suggest lumbar metastasis. ||
 * **Diagnostic Procedures:** || Lindsey

Initial workup for CNS tumors includes a complete history and physical. 2 Following history and physical, a complete neurological exam should be performed including assessment of mental condition, cranial nerves, coordination/cerebellar function, sensation, power and reflexes. Ophthalmoscopy checks for papilledema as a sign of increased intracranial pressure should also be done. For MRI, T1 weighted images with and without gadolinium contrast, T2 weighted images, and fluid attenuated inversion recovery (FLAIR) images are all most useful. T1 weighted images show anatomy more clearly as well as areas of contrast enhancement. T2 and FLAIR images are more sensitive for detecting edema and tumor hyperintensity. CT with contrast is also useful. Staging of the neuraxis is essential for neoplasms at high risk of spread to cerebrospinal fluid (CSF). Neuraxis imaging is usually achieved with gadolinium enhanced MRI of the spine. Spinal imaging is usually combined with CSF cytology for complete neuraxis staging. Biopsy is also recommended for CNS tumors. However, selected patients with imaging and symptoms consistent with low grade glioma may be followed closely without biopsy. || Oligodendrogliomas are distinctive, consisting of homogeneous, compact, rounded cells with distinct borders and clear cytoplasm surrounding a dense central nucleus, giving them a “fried egg” appearance. Unfortunately it is very hard to differentiate an oligodendrogliomas from other brain lesions solely by their clinical or radiographic appearance. These are primary glial tumors. It is very interesting that the Greek meaning of ‘oligo’ means “few” and ‘dendro’ means “trees”. 3
 * **Histology:** || Kevin

Histologic image of oligodendroglioma. 3 || Absence of lymphatics in the brain; therefore no lymphatic drainage due to the blood brain barrier. || Have a high rate of recurrence and gradually increases in grade over time. Rarely invades to surrounding tissue. Metastasis to the cerebral spinal fluid has been seen but very rare. 4 || Grading refers to the appearance of the tumor under a microscope. The grade gives an idea of how quickly the tumor may grow. Grade 2 is low-grade and Grade 3 is high-grade (anaplastic). There is no grade 1.
 * **Lymph node drainage:** || Kevin
 * **Metastatic spread:** || Jenn
 * **Grading:** || Jenn

Grade II: tumor grows and spreads slowly and the tumor cells look very much like normal cells. Often forms in the cerebrum.

Grade III: tumor grows quickly and tumor cells look different from normal cells. 4 ||
 * **Staging:** || Rachel

Oligodendrogliomas and other primary brain tumors are diagnosed and classified by grade instead of using a staging system. 5 ||
 * **Radiation side effects:** || Rachel
 * Short term: fatigue, loss of appetite and nausea. Skin rashes and hair loss often also occur. 6
 * Delayed effects: can include varying degrees of memory loss and impairment of reasoning or thinking. More rarely, patients can experience impairment of pituitary function or radiation necrosis (a collection of dead tumor cells and scar tissue).
 * Radiation necrosis can produce symptoms that are often very similar to the initial tumor presentation and includes severe headache, motor weakness, visual problems, or seizures. ||
 * **Prognosis:** || Brandon

The overall survival rate for Oligodendrogliomas is better than Astrocytomas or GBMs. In one study, 106 patients underwent surgery as their primary treatment and had a variety of different modalities as a part of their therapy. 7 These modalities included: surgery alone, surgery plus adjuvant radiation, surgery plus adjuvant chemo. 7 The average age of diagnosis was 43 years old with an average Karnofsky Performance Score (KPS) of 90.5 The overall survival median was 7.3 years with 62% of patients surviving to the 5 year mark. 7 || Oligodendrogliomas are treated similar to low grade Astrocytomas. If the tumor is small and able to be fully resected, no further therapy is needed and the patient is closely followed. 8 However, if the tumor is larger in size and/or a higher grade surgery is the primary treatment option followed by External Beam Radiation Therapy (EBRT). 8 The standard dose and fractionation is 60 Gray (Gy) in 30 to 33 fractions. The volume that is used for treatment is the preoperative volume plus a 2 to 3 centimeter (cm) margin. 8 Oligodendrogliomas have also been shown to be sensitive to chemotherapy as well. Common chemo drugs used are: procarbazine, CCNU, and vincristine (PCV). 8 || The TD 5/5 is representative of the dose for 5% complication rate in 5 years. 9
 * **Treatments:** || Brandon
 * **TD 5/5:** || Ashley


 * Lens: 1000cGy (Cataract)
 * Retina: 4500cGy (Blindness)
 * Optic Nerve: 5000cGy (Blindness)
 * Optic Chiasm: 5000cGy (Blindness)
 * Cochlea: 5500cGy
 * Pituitary: 4500cGy (Hypopituitarism)
 * Brainstem: 5000cGy (Infarction, Necrosis)
 * Spinal Cord: 4700cGy (Infarction, Necrosis)
 * Brain: 4500cGy (Infarction, Necrosis)

*Note: The information above is indicative of total organ limitations. ||
 * **References:** || Ashley
 * 1) Oligodendroglioma. University of Connecticut Health Center. http://radiology.uchc.edu/eAtlas/CNS/1766.htm. Accessed June 3, 2013.
 * 2) Chao KS, Perez CA, Brady LW. //Radiation Oncology Management Decisions//. 3rd ed. Philadelphia, PA: Lippincott, Williams, and Wilkins; 2011: 148-149.
 * 3) Uddin S. //Oligodendroglioma//. eMedicine. 2012. Available at: [] . Accessed: June 5, 2013.
 * 4) Dana-Farber Cancer Institute. Oligodendroglioma. Available at: [|https://www.dana-farber.org/Adult-Care/Treatment-and-Support/Oligodendroglioma.aspx#Cancer_Summary]. Accessed June 6, 2013.
 * 5) Oligodendroglioma. Healthline. Available at: [|http://www.healthline.com/galecontent/oligodendroglioma#3]. Accessed June 7, 2013.
 * 6) Oligodendroglioma. Colorado Cyberknife. Available at: []. Accessed June 7, 2013.
 * 7) Puduvalli VK, Hashmi M, McAllister LD, Levin VA, Hess K, Prados M, et al. Anaplastic oligodendrogliomas: prognostic factors for tumor recurrence and survival. Oncology. 2003; 65(3):259-266. Accessed June 7, 2013.
 * 8) Chao K, Perez C, Brady L. //Radiation Oncology Management Decisions//. 2 nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2002.
 * 9) Hall, E. //Radiobiology for the Radiologist//. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2012. ||

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