I. Overview
Allergic purpura is a common capillary allergic hemorrhagic disease. It is caused by the body’s metamorphic reaction to certain allergenic substances, resulting in extensive small vasculitis, followed by increased permeability and fragility of the vessel wall, bleeding and edema of subcutaneous tissues, mucous membranes and visceral organs. Allergens may be related to bacterial, viral or parasitic infections as well as food, certain drugs, etc. The clinical manifestations are mainly skin purpura, which may be accompanied by arthritis, abdominal pain and nephritis (purpura nephritis, occurring in 30% of cases). The disease can be seen at any age, but it is more common in children and adolescents, and in males than in females. The disease is most common in spring and autumn. The disease is prone to recurrence and there is no specific treatment.
Etiology
The etiology of the disease is still unclear, and it is difficult to determine the definite allergens, the factors that may be related to the development of the disease are
1, infection: this is the most common cause. Bacterial infections, viral infections, parasitic infections can be allergens.
2, food factors: eating fish, shrimp, crab, eggs, milk, seafood and other heterogeneous proteins.
3, drug factors: penicillins, sulfonamides, anti-tuberculosis drugs, antipyretic and analgesic drugs and other drugs.
4, vaccination: cowpox, typhoid, hepatitis and other vaccinations.
5, other factors: such as insect bites, cold, pollen inhalation, mental factors, etc.
III. Clinical manifestations
According to the different clinical manifestations, there are several types as follows.
1. Skin type: The most common type. The main manifestation is bleeding skin rash. The rash is common below the buttocks, appearing in batches, symmetrically distributed, varying in size, old and new, with maculopapular purpura or exudative erythema above the skin surface. It may be accompanied by urticaria, edema, polymorphic erythema, ulceration or necrosis.
2, joint type: purpura appears as painful swollen anterior/posterior joints, mostly seen in knee, ankle, elbow and wrist joints. The pain may be wandering and does not leave deformity after healing.
3, abdominal type: mostly seen in children, there is abdominal pain before and after the appearance of purpura, may be accompanied by nausea, vomiting, blood in the stool, but no abdominal muscle tension and rebound pain, showing the separation of symptoms and signs. It can also be complicated by intestinal loop. The abdominal pain is severe and should be distinguished from acute abdominal disease.
4, purpura nephritis: children are common, can occur before or after the appearance of purpura. About 30% of children will develop renal damage, often manifested as carnal or microscopic hematuria and positive urine protein. It appears most frequently 4-8 weeks after the onset of the disease. A small number of them may manifest as prolonged nephritis, nephrotic syndrome, chronic glomerulonephritis, and acute nephritis.
5.Mixed type: two or more of the above four types are present in combination.
6.Other rare types: In a few cases, the lesions involve the central nervous system, and severe headache, dizziness, vomiting, irritability, delirium convulsions, paralysis and coma may occur. Very few patients may have myocarditis, pleurisy, pulmonary hemorrhage, asthma, laryngeal edema, iritis, etc.
IV. Treatment
(A) Treatment principles
1. Try to remove allergic factors, pay attention to diet, and get rid of intestinal worms.
2, simple skin type can be used antihistamines, compound Lutin, calcium preparations, vitamin C.
3, mixed type can be used corticosteroids, purpura nephritis advocate the use of corticosteroids + immunosuppressant + anticoagulant combination therapy.
(II) Treatment points
1.Remove allergens
Stop using drugs and foods that may cause allergy (fish, shrimp, crab, egg, milk, seafood, etc.). Get rid of chronic lesions. If there are intestinal parasites, give deworming treatment.
2.General treatment
(1) Antihistamines: the efficacy is variable. Cetirizine 2.5mg-10mg once a day for 3~6 months.
(2) Improve vascular permeability drugs: rutin tablets, vitamin C and calcium preparations.
3.Adrenal glucocorticoids and immunosuppressants
Hormone is suitable for patients with severe skin damage of allergic purpura or joint type or abdominal type purpura. Prednisone 0.5-2mg/kg.d, hydrocodone 100-200mg or dexamethasone 5~10mg can be used for severe symptoms. The course of treatment is usually 1~2 weeks, and can be extended as appropriate for renal type, but generally not more than 2-3 months. Hormones are often ineffective for the renal type and do not prevent relapse. Patients with renal type can be treated with additional immunosuppressants (e.g. azathioprine 2-3mg/kg/d, cyclophosphamide 2-3mg/kg/d, raglan 20mg tid) for 2-3 months. Combination therapy with hormone and immunosuppressant can also be used.
4.Symptomatic treatment
Those with joint swelling and pain can take oral aspirin (do not use for patients with combined intestinal bleeding). If the abdominal pain is obvious, 654-2 can be injected; if the abdominal pain is suspected to be intestinal loop or intestinal perforation, timely surgery is needed. Gastrointestinal bleeding can be treated with omeprazole and, if necessary, diet restriction. Those with central nervous system involvement can be treated with high-dose corticosteroids and mannitol for dehydration.
5.Anticoagulants
In the acute phase of the disease, there are often varying degrees of hypercoagulability and abnormal levels of various coagulation factors. For patients with purpura nephritis, anticoagulant drugs can be added, such as dipyridamole (Pansentin) 2.5-5 mg/(kg?d), divided into three oral doses, for a period of 6 months. Heparin not only has anticoagulant and pro-fibrinolytic effects, but more importantly, it also inhibits glomerular thylakoid cells and endothelial cell proliferation; heparin itself has a large negative charge barrier, preventing albumin leakage. Heparin can play a more important role in the treatment of purpura nephritis. Specific usage: Normal heparin 100-150U/(kg/d) added to 5% glucose solution 100mL slowly intravenous infusion, once a day for 5-7 days; or low molecular heparin calcium (Speedy Bilin) 2500u subcutaneous injection, twice a day for 5-7 days.
6. Others.
Prostaglandin E also has a role in the prevention and treatment of purpura nephritis. Prostaglandin E1 can directly dilate the renal artery and make the glomerular filtration rate increase significantly. It can also inhibit the aggregation of platelets and release thromboxane A2 to prevent thrombosis. Usage: Add 100-200 μg of prostaglandin E1 to 250 ml of 5% glucose injection and take it as an IV once a day for 2 weeks.
Precautions.
1, because about 30% of patients can develop purpura nephritis during the course of the disease, it is best to check the urine once a week during the first two months of the disease.
2, the sooner purpura nephritis is treated, the faster it will improve.
The actual fact is that you can find a lot of people who are not able to get a good deal on a lot of things. It can also cause certain damage to the kidney, such as aggravating glomerular disease proteinuria, aggravating glomerular sclerosis, easily causing kidney calcification or stones, inducing or aggravating kidney infectious diseases, causing hypokalemic nephropathy, etc.
4, after treatment in purpura disappeared 1 month before the resumption of animal protein diet.
5.Antifibrinolytic drugs should be used with caution in those with renal lesions.
V. Prognosis
The prognosis of allergic purpura is good, usually improve within 6-8 weeks, some cases (40%) can recur, but the recurrence of the disease has a tendency to gradually slow down compared with the initial attack. In a few patients, the disease can be prolonged for several years. Most patients with renal involvement recover, while a few with severe involvement may cause renal failure and have a poor prognosis.