Definition: Unexplained joint swelling lasting more than 6 weeks in children under 16 years of age. Diagnostic points: I. Clinical manifestations Most of them have single or multiple joint swelling and pain. The systemic type may not show joint symptoms in the early stage of the disease, but show a variety of non-specific infection manifestations such as fever, rash, enlarged liver and spleen lymph nodes, and pluritis. Auxiliary tests: routine blood count, blood sedimentation, CRP, immune panel 6, autoimmune panel 3, organ function, rheumatoid panel, antinuclear antibody, pathogenic examination (such as blood culture, virus, mycoplasma, tuberculosis, etc.), ferritin, coagulation panel 4, bone marrow smear, joint X-ray or MRI, joint fluid analysis. C. Differential diagnosis 1. Systemic symptoms such as high fever and rash are the main symptoms (1) Sepsis: especially differentiate from so-JIA. (2) Tuberculosis: joint tuberculosis and spinal tuberculosis are more difficult to differentiate, and PPD, imaging examination, anti-tuberculosis hangers, T-SPOT, etc. are used as the basis for differentiation. (3) Viral infection: Viral infection is self-limiting and symptoms will subside with symptomatic support. (4) Malignant diseases: leukemia, lymphoma, malignant histiocytosis and other malignant tumors. Bone aspiration and related imaging examinations are required for differentiation. (1) Tuberculosis arthritis: PPD, imaging, anti-tuberculosis hangers, T-SPOT. (2) Septic arthritis: unilateral large joints, localized redness, swelling, heat, pain, systemic toxicity, turbidity of synovial fluid, pathogens are mostly gram-positive bacteria. (3) Rheumatic fever: Wandering arthralgia, streptococcal infection, and elevated ASO. (4) Traumatic arthritis: history of trauma, X-ray, joint ultrasonography. 3. Differentiation from other rheumatic diseases combined with arthritis (1) SLE: A significant proportion of JIA patients have positive ANA hangers, while SLE often has a typical facial butterfly rash and a high rate of kidney involvement. The majority of SLE patients have a combination of other autoantibodies, such as ds-DNA. (2) Vasculitis syndrome: These diseases, such as allergic purpura, although there may be significant joint pain and even impaired mobility, it often has a definite timing such as simultaneous attacks with purpura and is more common in the lower extremities as well as a history of allergy. (3) Psoriatic arthritis: psoriatic arthritis is mainly involving the distal joints of the fingers or toes, and joint deformities may also occur, but rheumatoid factor is negative, and there are skin or nail lesions associated with psoriasis. (4) Ankylosing spondylitis: This disease mainly affects the spine, but the peripheral joints can also be involved, especially the knee, ankle and hip joints as the first symptoms, need to be distinguished from rheumatoid arthritis. The disease has the following characteristics: (1) it is common in young men; (2) it mainly affects the sacroiliac joints and the spine, and the peripheral joints are mainly involved in the asymmetric joints of the lower limbs, often with tendonitis; (3) 90-95% of patients are HLA-B27 positive; (4) rheumatoid factor negative; (5) X-ray changes of the sacroiliac joints and the spine are extremely helpful for diagnosis. Treatment: The goal of treatment is to maximize the protection of daily functional activities of the child, relieve discomfort, prevent or reduce organ damage, and avoid or minimize drug toxicity. I. General treatment 1. In addition to temporary bed rest during the acute phase, the child should be encouraged and instructed to perform passive and active activities on the affected joints and engage in tolerable physical exercise. 2.In the acute stage, physical therapy such as ultrashort wave, heat therapy, warm water bath, spectrum and other instruments and rehabilitation by massage and tui-na. Psychotherapy is very important to encourage children to participate in normal activities and school to enhance their self-confidence. Symptomatic treatment 1.Systemic symptoms such as fever, swollen joints can be short-term use of corticosteroids (oral, intravenous, joint cavity injection); 2.The routine use of a non-steroidal anti-inflammatory drugs (NSAIDs), can more quickly reduce joint symptoms; 3.Chinese medicine treatment, can play a certain degree of anti-inflammatory, immunomodulatory, liver protection, can be used as an auxiliary treatment. Third, the allopathic treatment 1, the use of anti-rheumatic drugs to improve the condition (DMARDs), such as methotrexate, cyclophosphamide, cyclosporine A, etc., can affect the abnormal immune function and change the progress of the disease, reduce the degree of systemic and joint activity; 2, the use of biological agents, such as Etanercept, Adalimumab, Infliximab, etc., can effectively control the disease 2, the use of biological agents, such as Etanercept, Adalimumab, Infliximab, etc., can effectively control the activity of the disease and delay the destruction of the joints, mainly for children with refractory JIA; 3, the active formal treatment with drugs is not effective, consider surgical treatment, synovectomy is controversial in children. Prevention: The cause of the disease is not known, so it is impossible to predict the occurrence of the disease. Prevention of recurrence of the primary disease requires three major components: timely diagnosis, compliance with prescribed medication, and regular review.