[Analysis of the etiology and clinical characteristics of patients with hemophagocytic lymphohistiocytosis].

Objective: To explore the etiology of hemophagocytic lymphohistiocytosis (HLH) and analyze the clinical features, treatment options and outcomes of patients with HLH induced by infectious and non-infectious factors. Methods: The clinical data of 97 patients aged ≥14 years who were diagnosed or suspected of HLH during their hospitalization at Peking University First Hospital from January 1, 2006 to December 4, 2021 were retrospectively analyzed, and 80 patients with HLH were further screened for inclusion. The general condition and etiological composition of the patients were analyzed, and the laboratory tests, treatment and outcome of patients in the infection, tumor and autoimmune disease groups were compared. Results: The age[M(Q1,Q3)] of the 80 patients with HLH was 53.5 (32.0, 64.0) years, with a male-to-female ratio of 1∶1. Of the 80 HLH patients with HLH, 23.8% (19/80)、37.5% (30/80)、15.0% (12/80)、10.0% (8/80) were secondary to infection, neoplasm, autoimmune disease, and mixed factors, respectively, with EBV infection (n=15) and hematologic neoplasm (n=28) being the most common etiologies in infection or non-infection-related HLH. The incidence of peripheral blood secondary or tertiary lineage reduction was significantly higher in patients in the infection group than in the autoimmune disease group [68.4% (13/19), 33.3% (4/12), P=0.002]. Serum ferritin (SF) ≥500 µg/L and ≥1 500 µg/L were 93.1% (54/58) and 72.4% (42/58), respectively; among them, 29 patients had significantly lower SF after treatment than before treatment, 1 049 (362, 1 769)µg/L and 2010 (1 231, 7 323) µg/L (P<0.001). Phagocytosis was seen in 68.75% (55/80) and HLH-related gene mutations were detectable in 5 cases. In the three groups, 13.1% (8/61) of patients died of disease, 47.5% (29/61) improved and 9.8% (6/61) relapsed. Conclusions: HLH has no specific symptoms and progresses rapidly, mainly due to infections, neoplastic diseases, autoimmune diseases. The prognosis may be improved with early treatment.