[Etiology, Clinical Characteristics and Prognosis of Secondary Hemophagocytic Syndrome].

Objective: To understand the etiology, clinical characteristics and prognosis of secondary hemophagocytic syndrome (HLH), so as to improve the understanding of HLH and reduce the rates of misdiagnosis and missed diagnosis of HLH.

Methods: A retrospective study was conducted to analyze the cause, clinical characteristics, laboratory findings, therapy and outcomes of 75 adult patients with secondary HLH admitted to our hospital from January 2015 to December 2021. Follow-up continued until the last discharge time.

Results: Among 75 patients, infection-related HLH was the most common (45.33%), followed by lymphoma-related HLH (17.33%). Fever was the most common clinical manifestation (97.67%). Laboratory indicators such as NK cell activity (98.31% low or absent), sCD25 (93.22% increased), and serum ferritin (94.44% elevated) had higher sensitivity in diagnosis. By comparing the clinical manifestations and laboratory indicators of HLH patients with different causes, sex, lymph node enlargement and bone marrow morphology were more valuable for the diagnosis of primary disease (all P <0.05). By comparing the treatment and clinical outcomes of HLH patients with different causes, the highest clinical remission rate (83.3%) was achieved in patients with autoimmune disease-related HLH treated with hormone+cyclosporine (P <0.05). The overall 12-month survival rate of all patients was 26.7%, in which the infection-related HLH was the lowest (14.7%) while autoimmune disease-related HLH was the highest (63.6%).

Conclusion: The causes and clinical characteristics of adult secondary HLH are varied, with poor prognosis and heterogeneity in disease severity. It is important to identify HLH cause early for diagnosis and needed to further understand HLH.