Background: In acute lymphoblastic leukemia (ALL), central nervous system (CNS) involvement is a major clinical concern. Despite nondetectable CNS leukemia in many cases, prophylactic CNS-directed conventional intrathecal chemotherapy is required for relapse-free survival, indicating subclinical CNS manifestation in most patients. However, CNS-directed therapy is associated with long-term sequelae, including neurocognitive deficits and secondary neoplasms. Therefore, molecular mechanisms and pathways mediating leukemia-cell entry into the CNS need to be understood to identify targets for prophylactic and therapeutic interventions and develop alternative CNS-directed treatment strategies . In this study, we will analyze one of ADAM 28 enzyme to correlate its presence with CNS involvement in ALL patients.
Aim of the Work: The aim of the present study is to compare the ALL with CNS infiltration and without CNS infiltration and ADAM-28 overexpression in ALL and its relation to CNS involvement in adult Egyptian patients.
Patients and Methods: A prospective study. The study will be conducted on patients diagnosed as Acute Lymphocytic Leukemia ALL attending hematology  department of Ain Shams University. Six months. 50 patient (25  patient with ALL  and CNS infiltration , 25  patient with ALL  and  had No CNS infiltration).
Results: In the present study we found that there was no statistically significant difference between the studied groups as regards age and sex.  In our study we found that there was high statistically significant difference between the studied groups as regard BMI.  In our study we found that there was no statistically significant difference between the studied groups as regard Liver and kidney function tests. Also we found that there was no viral infection detected.  In our study we found that according to CNS infiltration there were 3 (15%) with CNS infiltration.  In the current study we found that in the follow-up there were 15 (75%) were alive and 5 (25%) were dead.
Conclusion: We conclude that adult patients with ALL who develop CNS recurrence have a very poor prognosis. ADAM28 expression levels also identified a new subgroup at a higher risk for relapse and with a poor prognosis in the favorable-risk patients, Although the disease in the CSF frequently responds to IT chemotherapy, most patients eventually develop a systemic recurrence and succumb to the disease. Effective CNS prophylaxis remains the best strategy for potential long-term survival. Prospective studies looking at better strategies to manage patients with this complication are needed.