What is vasculitis?
Vasculitis is a general term that refers to the inflammation of arteries, or blood vessels.
What is HSP?
Henoch-Schonlein purpura (HSP or anaphylactoid purpura) is a form of blood vessel inflammation or vasculitis. Each of the forms of vasculitis tends to involve certain characteristic blood vessels. HSP affects the small arterial vessels in the skin, gastrointestinal tract and frequently the kidneys. HSP results in skin rash, most prominent over the buttocks and behind the lower extremities associated with joint inflammation (arthritis), and cramping pain in the abdomen.
What are the symptoms?
Typical HSP skin rash
Classically HSP causes skin rash, pain in the abdomen, and arthritis. Patients with HSP can develop fever. Boys can develop painful scrotal swelling. Symptoms usually last between 2 - 12 weeks, typically about a month. Recurrences are not frequent but do occur.
Skin: purple, bruised rash on legs, buttocks or elsewhere. This is caused by red blood cells that leak out of the damaged blood vessels.
Joints: painful, brief swelling. The joints most frequently affected with pain and swelling are the ankles and the knees. Usually this only lasts from 1-3 days in the individual joints. Sometimes whole limbs will swell. The inflammation does not cause crippling arthritis.
Intestines: mostly abdominal pain, but can also include loss of appetite, diarrhea, vomiting and occasional blood in stools. Rarely, patients develop an abnormal bowel folding called intussusception.
Kidney: 50% of patients have kidney inflammation but less than 1 in 10 have permanent injury to the kidneys. Inflammation of the blood vessels in the kidneys can cause blood or protein in the urine.
What causes HSP?
HSP frequently follows an infection of the throat or breathing passages (often strep throat). HSP seems to represent an unusual reaction of the body's immune system which is in response to this infection (either bacteria or virus). HSP occurs throughout the year, but some studies have shown that there is an increase in cases during the fall and winter months.
Who is affected by HSP?
HSP is the most common acute vasculitis affecting children, with an incidence of approximately 10 cases per 100,000 children per year. Although the syndrome is usually seen in children, people of any age may be affected. It is more common in boys than in girls.
How is HSP diagnosed?
The diagnosis of HSP is based on a combination of factors, including a physical examination that reveals skin lesions and joint tenderness, urinalysis that shows microscopic blood in the urine, stool that shows microscopic blood, skin biopsy (usually not needed to diagnose) showing vasculitis, and lab tests to rule out alternative diagnoses.
How is HSP treated?
While HSP is generally a mild illness that resolves spontaneously, it can cause serious problems in the kidneys and bowels. The rash can be very prominent. The treatment of HSP is directed toward the most significant area of involvement. Joint pain can be relieved by tylenol or by anti-inflammatory medications, such as naproxen or ibuprofen. Some patients can require cortisone medications, such as prednisone, especially those with significant abdominal pain or scrotal edema.
What is the outlook?
The prognosis for patients with HSP is generally excellent. Nearly all patients have no long-term problems. The kidney is the most serious organ involved when it is affected. Rarely, patients can have serious long-term kidney damage. Very few patients have recurrences of symptoms for years after the onset of the illness. Recent data shows that HSP in adults is generally more severe than in children. Adults have more severe kidney involvement and can require more aggressive treatment. The ultimate outcome, however, is usually very good for both adults and children.
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