title: [A multicenter retrospective etiological analysis of 601 patients with hemophagocytic lymphohistiocytosis in China].
abstract: OBJECTIVE
  To investigate the prevalence and etiology of hemophagocytic lymphohistiocytosis (HLH) in different age groups.
  
  
  METHODS
  Clinical data of patients with HLH were retrospectively collected from June 2005 to March 2014 in 49 hospitals in China. These patients were divided into child, youth, middle-aged and elderly groups according to the age of onset; meanwhile divided into primary HLH group, infection-associated HLH group, tumor-associated HLH group, rheumatic disease-associated HLH group according to the etiology. Prevalence rates, gender and underlying diseases of each group were retrospectively analyzed.
  
  
  RESULTS
  A total of 601 patients were included in the study, age ranging from 1 month to 82 years. The median age of onset was 27 years and 26 years respectively in males(316 cases) and females (285 cases) without statistical significance (P=0.622). There were 171 in child group (28.5%); 262 in youth group(43.6%); 104 in middle-aged group(17.3%); 64 in elderly group(10.6%). The most common causes were infections in child group, malignancies and infections in youth group, malignancies in middle-aged group as well as elderly group. There were 48 patients in primary HLH group(8.0%), 197 in infection-associated HLH group(32.78%), 208 in tumor-associated HLH group(34.61%), 56 in rheumatic disease-associated HLH group(9.32%). Patients with primary HLH were significantly younger than those with secondary HLH (P<0.001), however the tumor-associated HLH group was the eldest. Primary HLH, infection-associated HLH and tumor-associated HLH had more male patients but without statistical significance (P=0.196), while rheumatic disease-associated HLH was mostly female patients (P<0.001).
  
  
  CONCLUSIONS
  HLH is not a disease peculiar to children, instead, it may occur in all ages. There are a variety of etiology in different age groups, and a possible link between sex and HLH development. In clinical practice, due attention should be paid to the patients with suspected HLH. Positive relevant inspections may aid in the final diagnosis.
authors.forename: Ruijun
authors.initials: R
authors.lastname: Pei
authors.affiliation: Department of Hematology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China; Email: bjyyxynk@163.com.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Wang
authors.forename: Yini
authors.initials: Y
authors.lastname: Wang
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Shi
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang
authors.forename: Huyong
authors.initials: H
authors.lastname: Zheng
authors.forename: Junling
authors.initials: J
authors.lastname: Zhuang
authors.forename: Xinan
authors.initials: X
authors.lastname: Cen
authors.forename: Lihong
authors.initials: L
authors.lastname: Li
authors.forename: Xuewu
authors.initials: X
authors.lastname: Zhang
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.forename: Yongqing
authors.initials: Y
authors.lastname: Zhang
authors.forename: Wanjun
authors.initials: W
authors.lastname: Sun
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D051359:Lymphohistiocytosis, Hemophagocytic / Q000175:diagnosis / Q000208:ethnology* / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications* / Q000208:ethnology; D015995:Prevalence; D012189:Retrospective Studies; D055815:Young Adult