Novel perspectives on the rare hemophagocytic lymphohistiocytosis: insights from a multi-center retrospective cohort.

Background and objective: Hemophagocytic syndrome, also known as hemophagocytic lymphohistiocytosis (HLH), is a rare clinical disease that is highly challenging to diagnose, has a low long-term survival rate and a high mortality rate. Currently, due to the particularity of HLH and the lack of effective understanding of the severity and prognosis of the disease in clinical practice, HLH patients are often missed or misdiagnosed in clinical practice, causing them to miss the best opportunity for diagnosis and treatment. This study aimed to retrospectively summarize and analyze the clinical characteristics, diagnosis and treatment, and prognosis of HLH patients from four medical centers, aiming to explore the risk factors affecting the prognosis of HLH patients and further enhance the understanding of HLH. Methods: The clinical data of 162 patients with HLH diagnosed in four medical centers from May 2017 to May 2025 were collected. The general conditions, laboratory results, diagnosis and treatment processes, and prognosis of these patients were analyzed, and univariate and multivariate analyses of prognostic factors were conducted. Results: A total of 162 HLH patients were included in this study, of whom 90 cases survived (55.56%), 72 cases died (44.44%), and there were 78 male patients (48.15%) and 84 female patients (51.85%), with a median age at onset of 52 years (range: 1-83 years). The most common etiological factor was Epstein-Barr virus (EBV) infection, and the primary presenting symptom was fever. First-line treatment primarily involved anti-infective therapy and symptomatic management, which was administered to 147 cases (90.74%). Prognostic analysis revealed that age, history of malignancy, infection history, presence of dermatological symptoms, APTT, INR, PCT, CRP, TG, TBIL, ferritin level, sCD25, lactate, SOFA score and time to treatment initiation, glucocorticoid monotherapy, gamma globulin treatment were significantly associated with patient outcomes in HLH. Tumor history, ferritin level, sCD25, lactate, SOFA score, time to treatment initiation, gamma globulin treatment were independent risk factors for mortality. Univariate Cox regression analysis identified that age, tumor history, history of rheumatic and autoimmune disorders, CRP, ferritin level, sCD25, lactate, SOFA score and time to treatment initiation, chemotherapy, glucocorticoid monotherapy, gamma globulin treatment were significant prognostic factors for OS in HLH patients. Multivariate analysis confirmed that tumor history, CRP, ferritin level, sCD25, lactate, SOFA score and time to treatment initiation, chemotherapy, glucocorticoid monotherapy, gamma globulin treatment were independent prognostic factors affecting OS in HLH patients. Age, APTT, INR, ferritin level, SOFA score, time to treatment initiation, glucocorticoid monotherapy, gamma globulin treatment were independent prognostic factors affecting OS in infection-triggered HLH patients. While age, INR, ferritin level, SOFA score, time to treatment initiation, chemotherapy were independent prognostic factors affecting OS in malignancy-associated HLH patients. Combined therapy regimens (especially chemotherapy combined with gamma globulin, glucocorticoid combined with gamma globulin) showed better clinical efficacy and survival benefits in the treatment of HLH. Conclusion: HLH is a rare clinical disease, EBV was the predominant trigger for HLH. Prognostic factors differed between infection- and malignancy-associated subgroups. Combined regimens, particularly those including gamma globulin, offered superior survival benefits, underscoring the need for etiology-specific treatment strategies.