Leukemoid reaction: A 21st‐century cohort study

• Published in: International journal of laboratory hematology 2020-04, Vol.42 (2), p.134-139
• Main Authors: Portich, Júlia P., Faulhaber, Gustavo A. M.
• Format: Article
• Language: English
• Subjects: Adult; Age Factors; Aged; Blood; Cohort analysis; Demography; Disease-Free Survival; Etiology; extreme neutrophilic leukocytosis; Female; Health risk assessment; Hemoglobin; Hemoglobins - metabolism; Humans; infection leukocytosis; Leukemoid reaction; Leukemoid Reaction - blood; Leukemoid Reaction - mortality; Leukocyte Count; leukocytosis; Male; Medical prognosis; Middle Aged; paraneoplastic leukemoid reaction; Patients; Prognosis; Retrospective Studies; Survival analysis; Survival Rate; Tumors
• ISSN: 1751-5521; 1751-553X
• DOI: 10.1111/ijlh.13127

Introduction Leukemoid reaction (leukocyte count >50 cells ×109 L) is a rare but extremely relevant finding. Since little has been published on this condition's clinical relevance and prognosis, we investigated leukemoid reaction in patients with a white blood cell count of >50 × 109 L, including etiology and outcomes. Methods This retrospective cohort study included all patients at a Brazilian tertiary hospital between January 2016 and July 2018 > 18 years with a total leukocyte count >50 cells×109 L. Demographics, complete blood count, clinical features, and the exams used to diagnose and determine leukemoid reaction etiology were analyzed. A Kaplan‐Meyer survival analysis was performed, and a binary logistic regression model identified variables associated with death. Results Of the 267 cases with white blood cell count of >50 × 109, 162/267 (60%) were secondary to hematopoietic neoplasm and 105/267 (40%) presenting as a true leukemoid reaction. The primary causes of the true leukemoid reaction cases were infection (59), nonhematopoietic neoplasm (17), or other causes (29). Patient deaths (66) differed significantly between groups (P