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2. CNS Disease in Pediatric Acute Lymphoblastic Leukemia Samar Muwakkit M.D. 2

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4. Introduction Contemporary risk directed treatment have improved 5 year event -free survival rates to more than 80% Even with such advances,CNS relapse still occurs in 3 -8% of children with ALL on contemporary protocols. CNS relapse remains a major therapeutic obstacle to cure in ALL. CNS relapse can be attributed to improved hematological control and to the reduced use of cranial irradiation to avoid long term sequelae. 4

5. Risk Factors for CNS relapse T- cell immunophenotype Hyperleukocytosis High risk genetic abnormalities like t(9;22) and t(4;11). The presence of leukemic cells in the CSF at diagnosis 5

6. Classification of CNS Disease CNS 1 : No detectable blast cells in CSF. CNS 2: <5 leukocytes per microliter with detectable blast cells in a cytocentrifuged preparation. CNS 3: 5 or more leucocytes per microliter with identifiable blast cells, or the presence of cranial nerve palsies. 6

7. Traumatic Lumbar Puncture 7