Sepsis Presenting as Hyperleukocytosis Mimicking Congenital Leukemia in a Preterm Neonate: A Case Report.

Neonatal sepsis continues to be a leading cause of mortality, frequently presenting with vague clinical characteristics. Rarely, it might present with hyperleukocytosis, which closely resembles congenital leukemia and creates a diagnostic difficulty. A preterm male neonate born at 34 weeks' gestation with a birth weight of 1.8 kg was delivered to a 27-year-old G2, P1 woman in a nonconsanguineous marriage. The neonate developed respiratory distress shortly after birth. Laboratory evaluation revealed a total leukocyte count of 108 × 103/µL (108 × 109/L), raising concern for congenital leukemia. However, peripheral blood smear showed cytoplasmic vacuolation and toxic granules without any blast cells, and flow cytometry excluded malignancy and leukocyte adhesion deficiency. Blood culture grew Acinetobacter baumannii A diagnosis of sepsis-induced hyperleukocytosis was made. The leukocyte count normalized with broad-spectrum antibiotics, and the neonate recovered fully. Hyperleukocytosis in neonates is not always indicative of congenital leukemia. Differentiating between malignant and reactive causes is crucial as management and prognosis differ widely.