OBJECTIVETo investigate the incidence, clinical symptoms, signs and laboratory features of childhood hemophagocytic lymphohistiocytosis (HLH) in China.

METHODSA retrospective study was performed on 217 pediatric patients with HLH who were admitted to Children's Hospital of Chongqing Medical University from January 2006 to April 2013. All patients'medical records were reviewed and analyzed.

RESULTSThe Male to female ratio was 1.11:1. The median onset age was 3 years and 5 months old (range of 6 months old to 16 years and 9 months old), and the age of onset peaked between 1-5 years old (61.3%). The most common causes of HLH was infection, especially Epstein-Barr virus-associated HLH (71.0%). Other causes included malignant hemophagocytic syndrome (MAHS), macrophage activation syndrome (MAS) and so on. The outstanding clinical manifestations including persistent fever (100.0%), hepatomegaly (92.6%), splenomegaly (88.4%), and more than half of cases with central nervous system involvement and pulmonary manifestations. Laboratory data indicated that the most prominent abnormality was elevated ferritin (98.0%), and the others were hemophagocytosis in bone marrow (90.7%) and coagulation abnormalities (76.5%). Abnormal lymphocytes classification is very common in HLH.

CONCLUSIONHLH is a heterogeneous disease, with a variety of the etiology and clinical manifestations. HLH-2004 diagnostic protocol had theoretical basis and clinical operability. The hepatitis damages related indicators, lymphocytes classification, central nervous system involvement and pulmonary performance can be used as reference value for HLH diagnosis.