Allergic Purpura
Allergic purpura (Henoch-Schönlein purpura) is a disease in which blood vessels in the skin, joints, digestive tract, or kidneys may become inflamed and leak.
Allergic purpura, an uncommon disease, affects mainly young children but can affect older children and adults. The disease is believed to be the result of an autoimmune reaction, in which the body attacks its own tissues. Usually, allergic purpura develops after a respiratory tract infection, but it can be caused by an allergic reaction to drugs. The rate at which the disease develops and its duration vary.
Symptoms and Diagnosis
The disease may begin with the appearance of small, bluish purple bruises (purpura)--most often on the feet, legs, arms, and buttocks--as blood leaks from vessels in the skin. Over several days, the purpura may become raised and hard; crops of new purpura may break out for several weeks after the first one appears. Swollen, achy joints are common, usually accompanied by fever. Bleeding in the digestive tract may cause abdominal cramps and pain. Blood in the urine (hematuria) may develop. Most people recover completely within a month, but symptoms may recur several times. Bleeding in the kidneys may cause kidney damage.
The diagnosis is based on the symptoms.
Treatment
A drug that may be causing an allergic reaction is discontinued immediately. Corticosteroids (for example, prednisone) may help relieve swelling, joint pain, and abdominal pain, but they do not prevent or reverse kidney damage. Drugs that reduce the activity of the immune system (immunosuppressive drugs), including azathioprine or cyclophosphamide, are sometimes used if kidney damage develops, but it is not known if they are helpful.
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