Halil Yildiz,1 Diego Castanares-Zapatero,2 Philippe d’Abadie,3 Sarah Bailly,4 Jean Cyr Yombi1 1Department of Internal Medicine and Infectious Diseases, Cliniques Universitaires Saint-Luc, UClouvain, Bruxelles, Belgium; 2Department of Intensive Care, Cliniques Universitaires Saint-Luc, UClouvain, Bruxelles, Belgium; 3Department of Nuclear Medicine, Cliniques Universitaires Saint-Luc, UClouvain, Bruxelles, Belgium; 4Department of Hematology, Cliniques Universitaires Saint-Luc, UClouvain, Bruxelles, BelgiumCorrespondence: Halil Yildiz, Department of Internal Medicine and Infectious Diseases, Cliniques Universitaires Saint-Luc, UClouvain, 10 Av Hippocrate, Bruxelles, 1200, Belgium, Email halil.yildiz@saintluc.uclouvain.beIntroduction: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease, which can be primary (due to genetic mutation) or secondary to malignancy, infection and rheumatologic diseases. Data concerning Belgian patients with adult HLH are lacking.Methods: This retrospective study was performed in a teaching hospital in Belgium. All cases of adult HLH, from December 2010 to April 2022, were reviewed. Patients with more than five HLH-2004 criteria and/or HScore > 80% were included in the study. The objective of our study was to describe clinical and biological characteristics of patients with HLH and attempt to look for variables associated with mortality.Results: Fifty-two patients were included in the final analysis. Mean age (SD) of patients was 48 (18) years old, and 29 patients were of male gender (56%). The underlying diseases associated with HLH were malignancy (M-HLH) in 22 patients, infection related HLH in 20 patients, rheumatologic disease related HLH in 7 patients, idiopathic in 2 patients and secondary to pregnancy in 1 patient. Overall mortality, mortality at 30 days and 90 days were 24/52 (46%), 13/52 (25%) and 4/52 (10%), respectively. In univariate analysis, malignancy, male sex, age and disseminated intravascular coagulation (DIC) were associated with mortality (p ...