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.