Overview
Allergic purpura is a common allergic reactive bleeding disorder. It mainly involves capillaries. There is no thrombocytopenia or coagulation disorder. In addition to cutaneous purpura, there may be abdominal, joint and renal involvement. It can be seen at any age, but is more common in children and adolescents, and is more common in males than females (2.5:1).
Etiology
Bacterial and viral infections: β-hemolytic streptococci are common among bacteria, followed by Staphylococcus aureus, Mycobacterium tuberculosis and Pneumococcus. Among viruses, influenza, rubella, chickenpox, mumps and hepatitis are the most common.
Parasitic infection: roundworm infection is the most common, followed by hookworm, and other parasites.
Food: mainly animal food, mainly fish, shrimp, crab, milk, eggs, chicken, etc.
Fourth, drugs: commonly used antibiotics (cyan, chain, chlorine, erythromycin), a variety of sulfonamides, antipyretic analgesics (salicylates, aminopyrine, botaxone, anacin), sedatives (phenobarbital, chloral hydrate, tranquilizer), hormones (synthetic estrogen, testosterone propionate, insulin), anti-TB drugs (isoniazid), other such as digitalis, quinidine, atropine, ketorolac, D860 Iodide, gold, arsenic, bismuth, mercury, etc.
V. Other: such as cold, trauma, insect bite, pollen, inoculation, tuberculin test, menopause, and even mental factors.
Symptoms
I. General symptoms: Most patients have a history of upper respiratory tract infection and symptoms 1-2 weeks before the onset of the disease.
Skin manifestations: The typical rash is brownish-red macules, protruding from the skin surface, not fading when pressed, alone or fused with each other, symmetrically distributed, more common on the extremities and buttocks, rarely invading the trunk, may be accompanied by itching or pain, appearing in batches, and may be left with pigmentation after fading. In addition to purpura, it can also be complicated by urticaria. Angioneurotic edema, erythema multiforme, or ulcerative necrosis. Occasionally, purpura may also appear in the oral mucosa or eye conjunctiva.
Joint manifestations: joints can have mild pain to obvious redness, swelling, pain and mobility disorders. The lesions often involve large joints, such as knees, ankles, elbows, wrists and other joints, and can be wandering, which is often misdiagnosed as “rheumatism”.
Abdominal manifestations: abdominal pain is common, mostly in the form of colic. The pain is obvious in the umbilicus and right lower abdomen, and can also spread throughout the abdomen, but generally no abdominal muscle tension, pressure pain is light, can be accompanied by nausea, vomiting, diarrhea and black stool. Irregular peristalsis of the intestine can lead to intussusception, and a mass can be found, mostly in children. Occasionally, intestinal perforation may occur. If not accompanied by skin purpura, it is often misdiagnosed as “acute abdomen”.
The kidney manifestation: nephritis is the most common complication of this disease, the incidence is 12-65%. It usually occurs within 1~8 weeks after the appearance of purpura, the severity varies, some are only transient hematuria, some progress to renal failure soon, but it is rare. The main manifestations are acute glomerulonephritis such as hematuria, proteinuria, tubular urine, swelling and hypertension, etc. A few cases may become chronic nephritis, nephrotic syndrome, and individual cases may turn into chronic renal failure.
The above four types (skin, joints, abdomen and kidney) can exist alone, and when two or more types are combined, they are called mixed types.
Examination
Blood picture: white blood cell count may increase, eosinophils increase; platelet count is normal, occasionally there is a mild decrease, but >80×109/L.
Hematological examination: normal bleeding and clotting time, good clot contraction, positive bundle arm test.
Immunological examination: serum IgA and IgG are often increased, the former is obvious; IgA-immune complexes are increased and IgA rheumatoid factor may be positive.
Urine: protein, red blood cells and tubular type may be present.
V. Other: Blood sedimentation is often increased. Urea nitrogen and creatinine may be increased in renal insufficiency.
Treatment
I. Remove the cause: It is important to find and remove the allergen.
Second, general treatment.
(I) Anti-allergic drugs: paracetamol 4mg orally three times a day; diphenhydramine or promethazine 25mg orally three times a day; reserpine 10mg orally once a day; 10% calcium gluconate 0ml sedation once a day.
(B) Vitamin C: can increase capillary resistance. The general dose of medication should be large. Vitamin C is better to be injected intravenously. Lutin 20-40mg, oral twice daily; vitamin C2-3g once daily intravenous injection or added to glucose solution intravenous drip.
(C) Hemostatic drugs: Aniloxin. Hemostatic min.
Adrenocorticotropic hormone: prednisone 30-40mg, orally once a day, in severe cases, hydrocodone 100-200mg or flumethasone 10-20mg intravenously daily for 3-5 days, and then orally after the condition turns.
IV. Immunosuppressants. For nephritis or complications of membranous or proliferative nephritis, if hormone alone is not effective, cyclophosphamide 2-3mg/kg/d by sedation, or azathioprine 2-3mg/kg/d orally, but attention should be paid to blood picture and other side effects. Pansentine may also reduce proteinuria.