Allergic purpura is a systemic vasculitis syndrome in which small vasculitis is the main pathological change. The combination of skin purpura, joint swelling and pain, abdominal pain, blood in stool and hematuria and proteinuria are the important features of this disease. Allergic purpura is the most common small vasculitis in childhood, most of them have a benign self-limiting process, but severe gastrointestinal, renal and other organ damage can also occur.
Why do you get allergic purpura?
So far, the etiology and pathogenesis of allergic purpura is not clear, the cause may involve infection, immune disorders, genetics and other factors.
1, infection : upper whistle infection is often the trigger factor for the occurrence of allergic purpura, the most common infection to hemolytic streptococcus, Helicobacter pylori, Staphylococcus aureus, parainfluenza virus, EB virus, micro virus B19 and other viral infections, other pathogens include Mycoplasma pneumoniae and so on.
2, vaccination: certain vaccinations such as influenza vaccine, hepatitis B vaccine, rabies vaccine, influenza vaccine, diphtheria vaccine, measles vaccine may also induce allergic purpura.
3, food and drug factors may trigger the occurrence of allergic purpura.
4, there is a genetic predisposition to allergic purpura, genetic polymorphism may also be related to the development of allergic purpura.
5, other triggering factors: cold stimulation, trauma, tuberculosis bacillus test and mental factors may trigger allergic purpura.
What are the manifestations of allergic purpura?
1, rash is a common symptom of allergic purpura, typical purpura may have a rash similar to urticaria or red papules before forming, symmetrical distribution on the extremities or buttocks, mainly on the extensor side; it may gradually spread to the trunk and face, and may form herpes. The rash can also be seen on the scrotum, penis, glans, palms and soles of the feet. Less than 5% of children with allergic purpura have skin necrosis; 35%-70% of young children may also have non-depressed scalp, face, dorsum of hand or dorsum of foot edema, some children also have neurovascular edema and pressure pain in the arms, gastrocnemius, dorsum of foot, around the eyes, scalp and perineum during acute attack, but rash is not the main complaint of all children, 30%-43% of children start with arthralgia or abdominal pain, which can be up to 14 days without rash. It is easy to be misdiagnosed because there is no rash for 14 days.
The incidence of joint involvement is 82%, mainly single, mainly involving both lower limbs, especially ankle and knee joints, without sequelae.
The incidence of gastrointestinal tract involvement is 50-75%, with mild abdominal pain and/or vomiting, but sometimes severe abdominal pain and gastrointestinal bleeding; occasionally there is massive gastrointestinal bleeding; intussusception is a rare complication.
4. The incidence of renal organ involvement is 20-60% and can be manifested as: microscopic hematuria and/or proteinuria; carnal hematuria is also common. Renal damage usually occurs within 6 months, with 91% of children having renal damage within 6 weeks and 97% within 6 months of the disease; renal damage can be transient and persistent.
5, neurological involvement accounted for 2%: headache is common, intracranial occupancy, hemorrhage or vasculitis have been reported, but rare.
6, pulmonary involvement <1%: interstitial pneumonia due to alveolar hemorrhage.
7, Children present with intramuscular hemorrhage, subconjunctival hemorrhage, recurrent epistaxis, mumps and myocarditis.
What should I do if I have allergic purpura?
1, when this disease occurs, actively look for possible causes and triggers and exclude some other diseases.
2, allergic purpura is self-limiting, simple rash usually does not require special treatment, then treatment includes control of acute symptoms and factors that affect the prognosis of the child, such as acute arthralgia, abdominal pain and kidney damage.
3, diet: in the early stage of allergic purpura avoid eating fish, shrimp, eggs, milk, crab, seafood and other foods that children are allergic to; some children may also be allergic to nuts, also use to control; avoid eating raw and cold apples, tropical fruits such as mangoes, pineapples on an empty stomach, other foods vary depending on the child’s previous allergy history; if there is no clear previous allergy history, meat, poultry do not need to be restricted, as long as you avoid frying, deep-frying, baking, snacks, drinks. Once the acute period is over and the rash does not appear in January, the diet can be gradually increased to normal; children need to supplement allogeneic high quality protein for growth, so they should not abstain from eating for a long time due to unnecessary worries.
4. Glucocorticoids are suitable for children with gastrointestinal symptoms of allergic purpura, arthritis, angioneurotic edema, severe renal damage and acute vasculitis manifested in other organs. Early application of hormones can effectively relieve abdominal and joint symptoms, significantly reduce abdominal pain, improve the rate of abdominal pain relief, possibly reduce the risk of intestinal entrapment and intestinal bleeding, and early application of hormones for children with severe abdominal symptoms is beneficial and may reduce the risk of surgical intervention.
What is the prognosis of allergic purpura?
1, allergic purpura is a self-limiting disease, most of them can be cured within 8 weeks, but it is easy to recur, the recurrence of the rash parents need not be overly nervous, pay attention to whether the child has joint swelling and pain, abdominal pain, stool color and traits have changed, if these symptoms need to see a doctor in time. There is no medicine that can prevent the recurrence of allergic purpura.
2, the prognosis of allergic purpura is mainly related to the gastrointestinal symptoms and nephritis, the recent prognosis is related to the gastrointestinal symptoms and the long term prognosis is related to the severity of the kidney involvement.
3, 85% of renal damage in children with allergic purpura occurs within 4 weeks of the disease, 91% occurs within 6 weeks of the disease, 97% occurs within 6 months, therefore, it is recommended that children with normal urine analysis should be followed up for at least 6 months, and those who still have abnormal urine examination after 6 months should continue to be followed up for 3-5 years.