Oligodendroglioma

Less common symptoms can include Grossly, oligodendrogliomas appear as well defined, solid, and pinkish grey, frequently with areas of calcification and sometimes with areas of necrosis and cystic degeneration[3]. Intratumoral hemorrhage may be present and in some patients may be massive and responsible for sudden death[3]. Microscopic 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[3]. See the image below. Histologic image of oligodendroglioma[3]. This image shows monomorphous tumoral proliferation that consists of round, regular cells with a small, central, hyperchromatic nucleus surrounded by clear cytoplasm. Few calcifications are present[3]. || The RTOG uses a staging system taking into account; age, Karnofsky performance, histology, mental status, extent of surgery, time between symptoms and treatment onset, neurologic function, and radiation therapy doses. [4] Yet another multifaceted system with room for error. Attatched is a karnofsky performance scale.  || With Oligodendrogliomas surgery and total resection is the gold standard of care. If this is not possible a subtotal resection also improves the outcome. Post-op radiotherapy may be used if the tumor is not completely resected or they are symptomatic.[6] The dose is 50-55 Gy in 1.8-2 Gy fractions. The treatment fields would include the tumor and a 3 cm. margin. [5] Oligodendrogliomas are sensitive to chemotherapy and that may be used instead of radiotherapy.[6] || || 2. McLendon RE. //Pathology of Oligodendrogliomas//. Medscape. Available at: emedicine.medscape.com/article/1743896-overview#aw2aab6b3. Accessed May 28, 2012. 3. Uddin S. //Oligodendroglioma//. eMedicine. 2012. Available at: []. Accessed: May, 30, 2012. 4. Washington, Charles M. //Principles and Practice of Radiation Therapy.// Third ed. St. Louis: Mosby; 2010 5. Chao, K.S. Clifford //Radiation Oncology Management Decisions.// Third ed. Philadelphia: LWW; 2011 6. Uddin S, Berman SA, Jarmi T, et al. Oligodendroglioma. Medscape web site. [|http://emedicine.medscape.com/article/1156699-overview#showall]. Feb. 3, 2012. Accessed May 31, 2012. 7. Emami B, Lyman J, Brown A, et al. Tolerance of normal tissue to therapeutic irradiation. //Int J Radiat Oncol Biol Phys.// 1991;109-122. []. Accessed May 31, 2012. || Back to Week 2
 * **Epidemiolgy:** || Usually oligodendrogliomas are tumors that affect young and middle-aged adults. [1] They represent an estimated 5% of all gliomas, with an incidence rate of approximately 0.28 per 100,000. Predominance in white and Hispanic individuals to black individuals with a 3-to-1 ratio has been recorded. Males are more likely to present with an oligodendroglioma than females. [2] ||
 * **Etiology:** || The cause of oligodendrogliomas is not well known. No pattern of inheritance or familial risk has been determined for the development of these tumors. [2] However, most tumors have shown abnormalities on chromosome 19 and 1. ||
 * **Signs & Symptoms:** || Signs and symptoms: the most common symptoms are headaches nausea and vomiting.
 * Bad vision
 * Changes in speech
 * Poor mental clarity
 * Clumsiness, poor balance, difficulty walking
 * Limb numbness or weakness ||
 * **Diagnostic Procedures:** || MRI is the preferred diagnostic method for identifying location and volume. MRI will be combined with several other methods to have a final stage, these include. * CT with or without contrast
 * PETCT
 * Biopsy
 * Angiogram ||
 * **Histology:** || Macroscopic
 * **Lymph node drainage:** || Since there is an absence of lymphatics in the brain, there is no lymphatic drainage due to the blood brain barrier. ||
 * **Metastatic spread:** || Oligodendroglioma metastatic spread is via cerebrospinal fluid[3]. Metastasis is rare but recurrence is high due to the infiltrating nature of gliomas[3]. ||
 * **Grading:** || The grade of a tumor is based on its aggressiveness of growth and cellular differentiation. Grade is determined by microscopic examination of tumor cells and is important in predicting the prognosis of a CNS tumor diagnosis. Grade and stage give the physician an accurate description of the tumor so that they may treat it effectively. CNS tumors can be grouped in to benign, low-grade or malignant, and high grade. A system known as the Kernohan Grading System, which is a four grade system has also been used. This system takes in to consideration; cellularity, anaplasia, mitotic figures, giant cells, necrosis, blood vessels and proliferation. Because of the many factors, this grading system is confusing and difficult to use.[4] ||
 * **Staging:** || There are no universal staging systems for CNS tumors which can be confusing and can lead to problems when diagnosing. The American Joint Committee on Cancer uses a GTM system; grade (G), Tumor type (T), and Metastasis (M).
 * **Radiation side effects:** || Depending on the location, treatment type, and extent of expansion around the tumor site, many side effects are possible but not all likely. Many of them include:
 * Nausea vomiting
 * Radiation dermatitis
 * Hair loss in treatment field
 * Inflammation of outer middle or inner ear and other ear damage, if in the treatment area, may cause temporary or permanent hearing loss.
 * Fatigue
 * Blood counts may decrease with large treatment volumes
 * Somnolence syndrome, occurs 6-12 weeks post radiation caused by damage to oligodendroglial cells.
 * Focal radiation necrosis can appear 6 months to years post radiation.
 * <span style="color: #7030a0; font-family: 'Times New Roman','serif'; font-size: 16px;">Cataracts, retinopothy if eye is included in field
 * <span style="color: #7030a0; font-family: 'Times New Roman','serif'; font-size: 16px;">Visual degradation if the optic nerve and or chiasm are included with blindness at doses of 50 to 55 Gy.
 * <span style="color: #7030a0; font-family: 'Times New Roman','serif'; font-size: 16px;">Hypothalamic-pituitary doses of 20 Gy or more can cause insuficiant hormone production. Brain irradiation can impact critical thinking, short term memory, and learning ability.[5] ||
 * **Prognosis:** || Oligodendrogliomas can be classified as low grade (grade II) or high grade (grade III). They have a good prognosis as compared to other parenchymal tumors, because they are less aggressive and respond well to chemotherapy. The average survival is 4-10 years.[6] ||
 * **Treatments:** || [[image:uwlmedicaldosimetry2012/oligodend.jpg width="560" height="340" caption="Oligodendroglioma"]]
 * **TD 5/5:** || ** TD 5/5 values from Emami 1991 [7] **
 * **References:** || 1. Lenhard RE, Osteen R, Gansler T. //The American Cancer Society’s Clinical Oncology//. Williston, VT: Blackwell Publishing, Inc; 2001.