Henoch-Schtinlein purpura (HSP) is the most frequent form of vasculitis in childhood, a systemic syndrome with mainly small vessel vasculitis as the pathologic change.The clinical manifestations of HSP are nonthrombocytopenic palpable cutaneous purpura with or without abdominal pain, gastrointestinal hemorrhage, arthralgia, and renal damage. Most present a benign self-limiting course, but severe gastrointestinal, renal, and other organ damage can also occur. Epidemiology HSP can occur in children of all ages, the smallest case reported as 6 months of age, but most common in 2 to 6 years old, 75% of patients younger than 8 years old, 90% of patients younger than 10 years old. The onset of the disease is common in the fall and winter seasons. The annual incidence rate of the disease in foreign countries is (10.5-20.4)/100,000 children. The annual incidence rate in Taiwan is 12.9/100,000, and there is no bulk epidemiologic incidence data reported in the mainland. The highest incidence rate was found in 4-6 years old, reaching 70.3/100,000 per year. The ratio of male to female incidence has been reported to be 1.2:1, with blacks having a slightly lower incidence than whites and Asians. Second, the etiology of 1, infection: upper respiratory tract infection is often the trigger factor for the occurrence of HSP. HSP most common infections to group A B hemolytic streptococcus caused by upper respiratory tract infections are most common, Helicobacter pylori (HP), Staphylococcus aureus and other infections may also be one of the reasons for the onset of HSP. HSP may also occur in relation to the parainfluenza, microvirus B19 and other viral infections one. Other pathogens, including Mycoplasma pneumoniae, may be associated with HSP. 2, vaccination: some literature reports that certain vaccinations such as influenza vaccine, hepatitis B vaccine, rabies vaccine, influenza vaccine, diphtheria vaccine, measles vaccine may also induce HSP, but reliable research evidence is needed to prove. 3, food and drug factors: some cases reported that the use of certain drugs such as clarithromycin, cefuroxime, minocycline, ciprofloxacin, diclofenac, propylthiouracil, hydrazine phenylpyridazine, allopurinol, phenytoin sodium, carbamazepine, isotretinoin, cytarabine, adalimumab, etanercept, etc. may also trigger the occurrence of HSP. HSP occurrence. However, there is no clear evidence that food allergy can lead to HSP. Genetic factors: HSP has a genetic predisposition, and the incidence rates of different races are different, with the incidence rate of Caucasians significantly higher than that of blacks. In recent years, the genetics research involves genes such as HLA genes, familial Mediterranean genes, angiotensin converting enzyme genes (ACE genes), mannose binding lectin genes, vascular endothelial growth factor genes, PAX2 genes, TIM-1 genes, etc. The literature has reported that the adhesion molecule P-adhesion factor (P-adhesion) can cause HSP. Literature reports that enhanced expression of the adhesion molecule P-selectin and gene polymorphisms may be associated with the development of HSP, and P-selectin gene promoter-2123 polymorphism may be associated with the development of HSP in children. Clinical features 1. Rash: It is a common symptom of HSP and is necessary for the diagnosis of HSP. Typical purpura formation may be preceded by a rash similar to urticaria or red papules, symmetrically distributed on the limbs or buttocks, with the extensor side predominating. It may gradually spread to the trunk and face, and may form herpes, necrosis and ulcers, or pinpoint hemorrhagic dots…. The rash can also be seen on the scrotum, penis, glans, palms of the hands and soles of the feet. Less than 5% of children with HSP have skin necrosis. Rash generally subside in a few weeks, can be left pigmentation, but will gradually fade. 35% to 70% of young children can also appear non-sunken scalp, face, dorsum of the hands or feet edema, acute attacks of some children still have arms, gastrocnemius muscle, dorsum of the foot, periocular, scalp, perineum, and other neurovascular edema and tenderness. 2, joint symptoms: rash is not the main complaint of all children, 30% to 43% of children with arthralgia or abdominal pain, can be up to 14d without rash, very easy to misdiagnose. The incidence of joint involvement is 82%, with a single joint as the main one, mainly involving both lower limbs, especially the ankle and knee joints, but erosive arthritis rarely occurs. Gastrointestinal symptoms: the incidence of gastrointestinal symptoms is 50% to 75%, including mild abdominal pain and (or) vomiting, but sometimes severe abdominal pain, occasional heavy bleeding, intestinal obstruction and intestinal perforation. Intussusception is a rare but serious complication with an incidence of 1% to 5%. In contrast to the typical ileocolonic location of idiopathic intussusception, HSP intussusception is ileocecal in 70% of cases and ileocolonic in 30%. There may also be rare mesenteric vasculitis, pancreatitis, cholecystitis, cholecystolithiasis, protein-losing enteropathy and subintestinal hematoma to intestinal obstruction. 4, renal damage: clinically, the incidence of renal involvement is 20% to 60%. Commonly, there are microscopic hematuria and (or) proteinuria, and carnal hematuria is also common, hypertension can be single or combined with renal lesions, acute glomerulonephritis or nephrotic syndrome accounted for 6% to 7% of the children with HSP, and acute renal failure can occur in severe cases. 5.Other system manifestations: reproductive system involvement is common with orchitis, and the incidence of HSP in boys is 27%. Nervous system involvement accounts for 2%, common headache, may appear convulsions, paralysis, chorea, movement disorders, aphasia, blindness, coma, subarachnoid hemorrhage, optic neuritis, Guillain-Barré syndrome, there are intracranial occupations, hemorrhage or vasculitis reported, but less often seen in the old. Pulmonary changes are rare in children (<1%), and pulmonary hemorrhage, alveolar hemorrhage, and questionable pneumonia have been reported. Intramuscular hemorrhage, subconjunctival hemorrhage, recurrent epistaxis, mumps and myocarditis have also been seen in children. There is no specific diagnostic method for anaphylactic purpura, and the relevant auxiliary examination only helps to understand the condition and complications, and the following examinations can be chosen according to the condition. 1, peripheral blood test: white blood cells are normal or increased, neutrophils can be increased. Generally, there is no anemia, but when gastrointestinal bleeding is serious, the anemia and platelet count may be normal or elevated. Erythrocyte sedimentation rate is normal or increased, C-reactive protein is elevated. Coagulation function test is usually normal, antithrombinogen-III can be increased or decreased, some children with increased fibrinogen content, D-dimer content. 2.Urine routine: there may be red blood cells, protein, tubular pattern, severe cases can be seen in the naked eye hematuria. Microscopic hematuria and proteinuria are the most common renal manifestations. 3.Blood biochemical examination: blood creatinine, urea nitrogen is normal in most cases, and can be elevated in very few cases of acute nephritis and acute progressive nephritis. Blood alanine aminotransferase (ALT), glutamic transaminase (AST) can be elevated in a few cases. Blood phosphocreatine kinase isoenzyme (CK-MB) may be elevated in a few cases. Blood albumin can be reduced in the combination of nephropathy or protein-losing enteropathy. 4, immunological examination: some children with elevated serum IgA, rheumatoid factor IgA and anti-neutrophil antibody IgA can be elevated. 5, imaging tests: ultrasonography, X-ray and CT examination, endoscopy, etc. 6, skin biopsy: for clinical rash atypical or suspected patients, skin biopsy can be used to assist in the diagnosis. Typical pathologic changes are leukocyte fragmentation vasculitis, perivascular inflammatory changes, neutrophil and eosinophil infiltration. There may be focal necrosis and platelet thrombosis in the vessel wall, necrotizing microarteritis, hemorrhage and edema in severe cases, and similar pathological changes in the gastrointestinal tract and joints. Immunofluorescence can see IgA, C3, fibrin, IgM deposition. V. Diagnostic criteria In 2006, the European League Against Rheumatism and the European Society of Pediatric Rheumatology formulated a new classification standard for vasculitis in children, which is referred to in this guideline. Treatment HSP is self-limiting and a simple rash usually does not require therapeutic intervention. Treatment includes control of acute symptoms and factors that affect prognosis, such as acute arthralgia, abdominal pain, and kidney damage. 1, general treatment: there is no clear evidence that food allergy is the cause of HSP, so only in HSP gastrointestinal damage need to pay attention to diet control, so as not to aggravate the gastrointestinal symptoms. HSP abdominal pain in children may exacerbate the symptoms of eating, but most of the children with mild disease can eat a small amount of less residue easy to digest food, severe abdominal pain or vomiting need to be nutritional elements of the diet or temporary fasting and extragastric nutritional support therapy. The patients with severe abdominal pain or vomiting need nutritional diet or temporary fasting and gastrointestinal nutritional support therapy. 2.Anti-infective treatment: Acute respiratory and gastrointestinal infections can be given appropriate anti-infective treatment, note that the acute infection control anti-infective treatment has no therapeutic and preventive effect on the occurrence of HSP. 3, rash treatment: rash rarely need treatment, there is no evidence to prove that glucocorticoid treatment is effective in the subsidence and recurrence of rash, but there are reports that glucocorticoid is used in the treatment of skin herpes and necrotic rash. 4, joint symptoms treatment: children with joint pain can be treated with nonsteroidal anti-inflammatory drugs for pain relief. In addition, oral prednisone [1 mg/(kg-d), tapered after 2 weeks] can reduce the degree of joint pain and pain duration in children with HSP arthritis [I/A]. 5, Treatment of gastrointestinal symptoms: glucocorticoid treatment can relieve gastrointestinal symptoms of acute HSP relatively quickly and shorten the duration of abdominal pain [II/B]. Hormones are also applied to other gastrointestinal symptoms, such as low-protein edema and gastrointestinal protein loss. 6, purpura nephritis treatment: purpura nephritis diagnosis and treatment with reference to the corresponding diagnosis and treatment guidelines formulated by the nephrology group of the pediatrics branch of the Chinese Medical Association. 7, the application of glucocorticoids: glucocorticoids for HSP gastrointestinal symptoms, arthritis, angioneurotic edema, renal damage is more serious and the performance of other organs of acute vasculitis children. It is currently believed that hormones are effective for HSP gastrointestinal and joint symptoms. 8, the application of other immunosuppressive agents and other treatments VII, prevention Active control of oral, ear, nose and throat infections, as well as tonsil and adenoidectomy for the recurrent recurrence of rashes and purpuric nephritis is effective in the treatment of a study of 40 cases of refractory allergic purpura in 31 cases of active control of oral and ear, nose and throat infections can promote its clinical remission, 9 cases of poor results (recurrent, persistent serious purpura or Nine cases with poor results (recurrent, persistent severe purpura or nephritis) were treated with tonsillectomy and methylprednisolone shock therapy with good results, and all of them were clinically cured, with no recurrence in the follow-up period of 2-10 years [V/E]. Prognosis The prognosis of anaphylactic purpura is mainly related to gastrointestinal symptoms and nephritis, the near-term prognosis is related to gastrointestinal symptoms, and the long-term prognosis is related to nephritis. It has been suggested that gastrointestinal symptoms also affect the long-term prognosis, and the incidence of functional gastrointestinal disorders (FGID) is higher in children with HSP who have abdominal pain and who have used glucocorticoids [III/D]. Purpura nephritis occurs in 20% to 60% of children with allergic purpura, and the long-term prognosis is related to the severity of renal involvement. The overall risk of developing end-stage kidney disease (ESKD) is less than 2%. Severe nephritis has been reported in up to 80% of children older than 4 years of age. In addition to age, severe abdominal pain and gastrointestinal bleeding, purpura persisting for more than 1 month, and decreased serum factor VIII are risk factors for renal involvement. Children who present with nephritic syndrome, nephrotic syndrome, or nephritic nephropathy at the onset of the disease develop end-stage renal disease in about 5% to 20%. Nine, follow-up HSP is a self-limiting disease, most of them can be cured within 8 weeks, but the recurrence rate within one year is about 30%～40%. Kidney damage in children with HSP occurs in 85% of cases within 4 weeks, 91% within 6 weeks, and 97% within 6 months [I/A]. Therefore, it is recommended that children with normal urinalysis be followed up for at least half a year, and those with no abnormalities in urinalysis after half a year of follow-up seldom see long-term kidney damage, and those with abnormalities in urinalysis after 6 months need to continue to be followed up for 3 to 5 years.