摘要Objectives Beh?et's syndrome(BS)is a rare disease of unknown etiology,with limited reports especially in pediatric BS.The clinical characteristics and phenotypes of pediatric BS as a highly heterogeneous variable vessel vasculitis were inves-tigated in this study.Methods A cross-sectional study was conducted to compare clinical variables and descriptive characteristics of BS by age of onset and gender.Cluster analysis was then performed to identify the phenotypes of pediatric BS.Results A total of 2082 BS patients were included in this study,1834 adults and 248 children.Compared with adult-onset BS,pediatric BS had a higher incidence of folliculitis[relative risks(RR)and 95％confidence interval(CI)1.3(1.0-1.5)],uveitis of the left eye[RR and 95％CI 2.3(1.0-5.0)],intestinal ulcer complications[RR and 95％CI 2.1(1.1-4.2)],pericarditis[RR and 95％CI 2.5(1.0-6.2)],and psychiatric disorders[RR and 95％CI 2.8(1.0-7.9)],while the incidence of thrombocytopenia was lower[RR 0.2(0.1-1.0)].Among pediatric BS,females had more genital ulcers,while males were more likely to have skin lesions,panuveitis,vascular involvement,venous lesions,cardiac involvement,and aortic aneurysms.Cluster analysis classified pediatric BS into five clusters(C1-C5):Cl(n=61,24.6％)showed gastrointestinal(GI)involvement;C2(n=44,17.7％)was the central nervous system(CNS)type where 23 cases overlapped joint involvement;in C3(n=35,14.1％),all patients presented with arthritis or arthralgia;all patients in C4(n=29,11.7％)manifested ocular involvement,with a few patients overlapping with GI involvement or joint damage;C5(n=79,31.9％)was the mucocutaneous type,presenting both oral ulcers,genital ulcers,and skin lesions.Conclusions The clinical features of pediatric and adult BS differ significantly.Male and female pediatric BS also have a distinct demography.Five phenotypes including GI,CNS,joint,ocular,and mucocutaneous types were identified for pedi-atric BS.