Objective: To determine the role of CD58 marker in Minimal Residual Disease (MRD) 
monitoring in B-cell Precursor ALL patients at South Egypt Cancer Institute (SECI). 
Methodology: This study was carried out in Department of Clinical pathology, South Egypt 
Cancer Institute, from October 2017 to December 2019. We used SECI Flowcytometry lab 4 
color acute leukemia panel for diagnosis, then we studied the role of CD58 in detection of 
MRD by applied it twice; at diagnosis and at day21 (post induction). Results: 50 patients 
were included in our study with acute lymphoblastic leukemia (ALL) who underwent CBC, 
BM aspiration and immunophenotyping. The mean age was 9.14±5.53 years. It included 31
(62%) males and 19 (38%) females. MRD by CD58 was positive in 18 (36%) of patients 
while was negative in 32 (64%). CD58 show sensitivity of 100%, specificity of 97%, positive 
predictive value of 94.4% and negative predictive value of 100% whereas the overall 
diagnostic accuracy of CD58 in MRD detection in ALL patients was calculated to be 98%.
Conclusion: CD58 showed a high sensitivity to assess MRD in ALL patients, so its use to 
detect MRD in ALL is very useful.