Leukemoid Reaction: Presentation of Two Cases

The leukemoid reaction is defined by the presence in peripheral blood of white cells above 50,000/mm3 or neutrophils above 30,000/mm3 . The frequency varies between 1.3 and 15% of newborns admitted to neonatal intensive care units [1]. It usually appears during the first two weeks of life and more frequently during the first four days, the duration is about 8.5 days [2]. In extremely premature, this process is produced by an inflammatory response that active cytokines who increased granulocyte colony-stimulating factors (G-CSF). These induce the production of neutrophils that cause hyperleukocytosis. These cytokines are produced in diseases related with prematurity such as brain white matter injury, respiratory failure with progression to bronchopulmonary dysplasia or necrotizing enterocolitis. The leukemoid reaction is also associated with the administration of neonatal steroids, infections, severe anemia and bronchopulmonary dysplasia [2,3]..