Leukomoid Reaction and Partial Exchange in an Infant with Pertussis

Introduction: Leukemoid reactions resulting from infections other than leukemia can present with serious clinical conditions. Pertussis infection, particularly before vaccination, can lead to severe pneumonia and may trigger a leukemoid reaction. This case is presented to highlight the relationship between severe pneumonia and leukemoid reaction in pertussis. Case Presentation: A 41-day-old baby girl, who had not yet been vaccinated against pertussis, was hospitalized in the pediatric intensive care unit with a diagnosis of severe pneumonia due to pertussis infection and required mechanical ventilation. A pronounced leukemoid reaction (144,000 cells/μL) was observed. Despite hydration and supportive treatment, a partial exchange was performed due to the elevated white blood cell count. Although there was partial improvement in the white blood cell count, the patient passed away on the 11th day of follow-up. Conclusions: There is a need for further case reports to determine the appropriate timing for initiating partial exchange treatment and the number of cycles required.