RÉSUMÉ
Beta-2 microglobulin has been claimed to be useful marker for the diagnosis of CNS infiltration, and also for early detection of subclinical CNS leukemia. The aim was to assess the value of B2m in CSF of children with ALL. The study was conducted on 23 patients with ALL, 13 newly diagnosed, 5 with systemic relapse and 5 with CNS relapse. The peripheral blood and bone marrow were examined. Serum and cerebrospinal fluid B2m were estimated for all patients on admission, before and after intrathecal therapy. CSF-B2m was significantly higher in patients with leukemic CNS infiltration. There was no significant correlation between CSF and serum B2m levels. CSF/serum B2m ratio was more than one in cases with isolated CNS relapse, and less than one in all other cases. There was an early elevation in CSF B2m in one case before development of overt CNS relapse. There was no significant change in CSF-B2m before and after ITC. The level of serum B2m after systemic chemotherapy was significantly lower than before treatment. Thus, serial CSF counts, protein and glucose, cytology and B2m are recommended to be used together with the clinical and radiological data to improve the diagnosis and management. Furthermore, CSF serum B2m ratio is recommended to be used for diagnosis of leukemic CNS infiltration when it is more than one