Hemophagocytic lymphocytosis (HLH) is a rare clinical and biological entity that can be life-threatening. Early diagnosis can improve the overall prognosis of HLH.

The aims of this study are to evaluate the performances of HLH-2004-score and H-score in identifying patients with secondary HLH and to determine an optimal H-score cut-off for our population.

A retrospective study that involved all patients, with images of hemophagocytosis in myelograms analyzed at the laboratory of hematology, followed at these departments: clinical-hematology, internal-medicine, infectious-diseases and gastroenterology, University-Hospital "Hédi-Chaker", Sfax-Tunisia, (June2017-May2021). We identified two groups of patients: "HLH" and "Not-HLH". Then, for each patient, we calculated the HLH-2004-score and the H-score.

Forty-two patients were included in this study. Twenty-five (60 %) belonging to group "HLH" and seventeen (40 %) to group "Not-HLH" with a mean age (38.72 vs. 39.82 years, p = 0.846) respectively. The study of the performances demonstrated that H-score had better performances. The best cut-off value of H-score for our population was 158.5, allowing a gain in sensitivity (from 92 % to 96 %) compared to the original study cut-off of 169.

Both H-score and HLH-2004-score showed excellent discriminative powers with better performances for H-score. The new H-score cut-off at 158.5 can be applied to our population.