Epidemiology:
According to Central Brain Tumor Registry of the United States database the proportionate distribution of CNS Lymphoma among other CNS tumors is 3.1%.¹⁰
Etiology:
Family history, Immunosuppression.⁸
Signs & Symptoms:
Focal presentation related to tumor location.⁹
Diagnostic Procedures:
Workup as detailed by Chao, et. al. includes: complete history and physical, complete neurologic evaluation, CT or MRI head scan (or both) with contrast, positron emission tomography (PET) scan, complete blood count, cerebral spinal fluid chemistry tests, cytology and microbiology studies. Neurologic exam includes mental condition, coordination, sensation, reflexes and motor + cranial nerves. Ophthalmoscopy to check for papilledema, which indicates intracranial pressure, and to assess any ocular involvement from the lymphoma. MRI contrast scan of the complete neuraxis for staging. Cerebral spinal fluid (CSF) cytology should be performed for any tumor that typically spreads through the CSF.This is particularly true of germ call tumor, primary neuroectodermal tumors (PNET), medulloblastoma and central nervous system (CNS) lymphoma.¹ Serology tests should be run to determine the presence of Epstein-Barr virus and HIV.²
Histology:
Central nervous system lesions are normally grouped by the World Health Organization into12 classifications: neuroepithelial tumors, choroid plexus tumors, neurologic tumors, pineal parenchymal tumors, embryonal tumors, cranial/spinal nerve tumors, meningeal tumors, mesenchymal tumors, uncertain histogenesis, cysts and tumor like lesions and sellar tumors.³ Primary CNS Lymphoma is, however, is classified as nonglial with more than 95% of CNS lymphomas are composed of large B-cell lymphoctyes.⁴ CD3+ T-cells can also be present.⁵ The neoplasms are usually intermediate- or high-grade lymphomas.⁶
Lymph Node Drainage:
There is no lymphatic vasculature in the CNS and tumors of the CNS do not metastsize through lymphatics.⁷
Metastatic Spread:

The most common site for a CNS lymphoma is the cerebrum, but it can also spread to other parts of the brain. ¹⁷

Grading:
PCNSL is now known to be a form of extranodal high-grade non-Hodgkin B-cell neoplasm, usually large cell or immunoblastic type. ¹⁸
Staging:
PCNSL is now known to be a form of extranodal high-grade non-Hodgkin B-cell neoplasm, usually large cell or immunoblastic type. It originates in the brain, leptomeninges, spinal cord, or eyes, typically remains confined to the CNS, and rarely spreads outside the nervous system. Therefore, it can be classified as stage 2 disease.¹⁷
Radiation Side Effects:
General side effects include nausea and vomiting, radiation dermatitis, alopecia, mucositis, esophagitis, fatigue, and decreased blood counts. If the ear is included, otitis externis, and high tone hearing loss can result. If the eye is treated then cataract formation can result as well as changes in visual acuity, visual field, or blindness in doses above 54 Gy.
Doses as low as 20Gy can produce hormone insufficiency.
Cranial treatment can result in decreased learning ability, deficits in short term memory, and difficulties with problem solving.
6-12 weeks after radiation, neurologic deterioration may occur and usually responds to steroid treatment.
Late reactions occur after 6 months, and peak at 3 years. The most serious is radiation necrosis which can mimic tumor recurrence. It can be controlled with surgery and steroids.¹⁵

Prognosis:
Prognostic factors include age, tumor type, tumor grade, seizure symptoms, duration of symptoms, performance status, extent of surgery performed, and irradiation dose.¹⁶
Treatments:
For non-immunosupressed patients, whole brain irradiation of 40-50 Gy is recommended. There may or may not be a boost to primary tumor to a total of 60-65 Gy. The posterior orbits should be included in the field. For patients with ocular involvement, the eyes should be treated as well with shielding to the anterior and lacrimal sections following 30-40 Gy.
If there is documented CNS involvement, then craniospinal radiation or intrathecal chemotherapy is recommended.
For immunosupressed patients, especially with poor prognostic indicators like CD4 lymphocyte counts of less than 200, or advanced AIDS, a shorter radiation course of 36-40 Gy should be used.
Usually a combination of chemotherapy and radiation proves best for long term control. Good results have come from use of methotrexate followed by cranial irradiation and intravenous sytarabine. Other chemotherapy agents include cyclophosphamide, doxorubicin, vincristine, and prednisone.¹⁵

TD5/5:
CNS_and_Medullo.jpg
Table 1. 5/5, TD50/514
CNS_Lymphoma.jpg
Figure 1. CNS Lymphoma BrainLab Treatment Plan

Copy_of_CranioSpinal.JPG
Figure 2. CranioSpinal Treatment Fields

Whole_Brain.JPG
Figure 3. Whole Brain Treatment Field


References

1. Chao KS, Perez CA., Brady LW. Radiation Oncology - Management Decisions. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2002:132-133.
2. Chao KS, Perez CA., Brady LW. Radiation Oncology - Management Decisions. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2002:151-152.
3. Chao KS, Perez CA., Brady LW. Radiation Oncology - Management Decisions. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2002:134.
4. Nelson DF, Jenkins RB, Scheithauer BW, et. al. Central nervous system tumors. In: Rubin P, ed. Clinical Oncology: A Multidisciplinary Approach for Physicians and Students. 8th ed.Philadelphia, PA: W.B. Saunders Company; 2001:798.
5. Nelson DF, Jenkins RB, Scheithauer BW, et. al. Central nervous system tumors. In: Rubin P, ed. Clinical Oncology: A Multidisciplinary Approach for Physicians and Students. 8th ed.Philadelphia, PA: W.B. Saunders Company; 2001:798.
6. Chao KS, Perez CA., Brady LW. Radiation Oncology - Management Decisions. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2002:151-152.
7. Adams RD, Langlin L, Leaver D. Central nervous system. In: Washington CM, Leaver D, eds. Principles and Practice of Radiation Therapy. 2nd ed. St. Louis, MO: Mosby; 2004:726-727.


8. Philip Rubin, Clinical Oncology - A Multidisciplinary Approach for Physicians and Students. 7th edition. Philadelphia, PA: W.B. Saunders Company. 1993.
9. Washington CM, Leaver D, eds. Principles and Practice of Radiation Therapy. 2nd ed. St. Louis, MO: Mosby; 2004.

10. Devita, Hellman, Rosenberg's. Cancer-Principles and Practices of Oncology. 8th ed. Philadelphia, PA: Lipincott, Williams & Wilkins; 2008.

11. Novalis Shaped Beam Surgery Center http://www.novalisaz.org Accessed January 13, 2010: Figure 1
12. Chao KS, Perez CA., Brady LW. Radiation Oncology - Management Decisions. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2002: Figure 2

13. SCTRC 01/14/10: Figure 3
14. Wikibooks en.wikibooks.org TD5/5 adapted from Emami 1991
15. Chao KS, Perez CA. Brady LW. Radiation Oncology - Management Decisions. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins. 2002
16. Washington CM, Leaver D. Principles and Practice of Radiation Therapy. 2nd ed. St. Louis, MO: Mosby. 2004

17. Chao KS, Perez CA., Brady LW. Radiation Oncology- Management Decisions. 2nd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2002
18. www.cancer.net/CNS/Lymphoma. Accessed January 11, 2010

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