Discordant Transient Extreme Hyperleukocytosis in Dichorionic Diamniotic Twins: The Role of the Sex?

Although a leukemoid reaction is a well-recognized phenomenon in the neonatal intensive care unit, transient extreme hyperleukocytosis in premature infants is rare. The exact mechanism is still unclear and several hypotheses are documented in the literature. In this case report, we describe 2 dichorionic diamniotic premature twins, of whom the 2 girls had extreme hyperleukocytosis, whereas their siblings did not, emphasizing the potentially important role of the sex in this phenomena.