What is allergic purpura?
Allergic purpura is a systemic vasculitis with systemic small vasculitis as the main manifestation, it is common in children and adolescents, the general age of onset is 5~14 years old, and the incidence is increasing year by year in recent years. The incidence of allergic purpura can occur throughout the year, but it is mostly seen in spring and autumn, and also in winter. The typical allergic purpura rash is characterized by a purple-red rash, which is higher than the skin surface and does not fade when pressed, mostly on the extremities and buttocks, but rare on the trunk, sometimes accompanied by abdominal pain, arthralgia, hematuria, proteinuria.
How does allergic purpura occur?
”When many people hear ‘allergic purpura’, they often look at the term and think it is caused by ‘allergies’.” Although allergic purpura is related to “allergy”, it is not the same thing as “allergy” in the traditional sense. The immune mechanism of allergic purpura is the deposition of IgA complexes in the skin, intestines and glomeruli leading to local inflammatory reactions, causing leukocyte fragmentation vasculitis and eventually leading to small vessel necrosis.
The pathogenesis of allergic purpura is not fully understood, and the common pathogenic triggers can be divided into four major categories.
1, infection.
Precursor respiratory tract infection is its most common trigger, including bacteria, virus, mycoplasma, etc.
2, Food.
Consumption of allergy-prone foods such as fish, shrimp, egg and milk, nuts, peanuts, soybeans, wheat, sesame, tomatoes, pineapples, bananas, mangoes, peaches, strawberries, food additives, etc., also predispose to the development of the disease.
3, drugs.
Certain drugs such as antibiotics, sulfonamides, aspirin, anesthetics, contrast agents, etc.
4, Other.
Including pollen, mosquito bites, vaccination, cosmetics, animal dander, etc. may lead to the occurrence of purpura.
What are the clinical manifestations of allergic purpura?
According to the characteristics of clinical manifestations of children, allergic purpura can be divided into 5 types.
1, simple purpura type.
Clinical manifestations are symmetrical purplish red petechiae, petechiae like rash on the limbs, buttocks, behind the ears, penis, perineum, etc., size varies, can be fused into pieces, or slightly above the skin surface, most of them are painless and itchy, the rash can fade within a few days, then recur in batches, some serious patients have rash fused into blood blisters, the middle is a hemorrhagic necrotic foci, or combined infection appears purulent secretions.
2. Joint type.
In addition to the rash, some patients develop joint swelling and pain, which can be fixed or wandering, with localized pressure pain, redness and swelling, mostly in the knee, ankle and large iliac joints, and a few in the elbow, wrist and finger joints, etc. Children may be reluctant to stand or walk due to joint swelling and pain. The swollen and painful joints can recur, and most of them will improve within a few months without leaving any sequelae.
3.Abdominal type.
The main manifestation is diffuse abdominal pain, located in the umbilical region or lower abdominal region, with paroxysmal colic or persistent dull pain, which can be accompanied by nausea, vomiting, diarrhea, constipation, blood in the stool and other gastrointestinal symptoms, and in serious cases, intestinal overlap, intestinal perforation, intestinal necrosis, etc.
4, renal type.
Also known as purpura nephritis, kidney damage generally occurs within two weeks to one month after the appearance of the rash, with clinical manifestations of hematuria and/or proteinuria.
5.Mixed type.
Two or more types co-exist as mixed type.
How to prevent and treat allergic purpura?
The course of allergic purpura is mostly self-limiting, but some of the clinical manifestations are more severe and need active treatment. However, there is no uniform treatment plan, mainly symptomatic treatment, including anti-allergy, anticoagulation, blood circulation and blood stasis, kidney protection and other treatment.
”Because children with allergic purpura are in a hypersensitive state during the acute period, various factors stimulating the body are likely to lead to repeated or aggravated purpura, joint or abdominal symptoms, and repeated purpura can aggravate kidney damage, so children with allergic purpura need to take preventive measures.”
The following points should be noted in daily life.
1, prevention of infection is the key.
Infection can cause recurrence of purpura, especially in autumn and winter, the temperature is variable and infection always comes quietly, so need to take extra precautions; some children with heavy skin damage, skin necrosis or ulcers can occur, skin disinfection is needed to prevent infection.
2, control diet.
Allergic purpura children in the acute stage is recommended to light hypoallergenic diet, avoid using too much ingredients in food, avoid fried food, small snacks and allergy-prone food.
3. Avoid contact with suspected allergens.
Paintbrush, chemical fiber clothing, cosmetics, new toys may contain harmful chemicals, children with allergic purpura should avoid contact, intimate clothing as far as possible to choose pure cotton products.
4, Other.
The acute stage of purpura children’s blood vessel fragility is poor, too much activity, skin local excessive pressure or temperature stimulation (such as washing feet with too hot water) are easy to cause purpura repeated, should pay attention to protection.