目的了解继发性噬血细胞综合征（HLH）的病因、临床特点及预后，以提高对HLH的认识，降低HLH的误诊、漏诊率。 2015年1月至2021年12月，我院收治的75例继发性HLH成人患者的实验室检查结果、治疗和结局。随访持续至最后一次出院时间。75例患者中，感染相关的HLH最常见（45.33%）其次是淋巴瘤相关的 HLH（17.33%）。发热是最常见的临床表现（97.67%）。 NK细胞活性（98.31%低或缺失）、sCD25（93.22%升高）、血清铁蛋白（94.44%升高）等实验室指标诊断敏感性较高。通过比较不同病因HLH患者的临床表现和实验室指标，性别、淋巴结肿大、骨髓形态对原发病的诊断更有价值（均P<0.05）。通过比较不同病因HLH患者的治疗和临床结局，自身免疫性疾病相关HLH患者接受激素环孢素治疗后临床缓解率最高（83.3%）（P <0.05）。所有患者总体12个月生存率为26.7%，其中感染相关HLH最低（14.7%），自身免疫性疾病相关HLH最高（63.6%）。 成人继发性HLH的病因及临床特点HLH 多种多样，预后较差且疾病严重程度存在异质性。早期确定 HLH 病因对于诊断非常重要，并且需要进一步了解 HLH。

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.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.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%).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.