Henoch-Schonlein Purpura (HSP)

HSP causes skin rash, pain in the abdomen, and joint inflammation (arthritis).

Henoch-Schonlein purpura (HSP) is a form of blood vessel inflammation or vasculitis. There are many different conditions that feature vasculitis. Each of the forms of vasculitis tends to involve certain characteristic blood vessels. HSP affects the small vessels called capillaries in the skin and frequently the kidneys. HSP results in a purplish skin rash (most prominent over the buttocks and behind the lower extremities) associated with joint inflammation (arthritis) and sometimes cramping pain in the abdomen. Henoch-Schonlein purpura is also referred to as anaphylactoid purpura.

HSP occurs most often in the spring season and frequently follows an infection of the throat or breathing passages. HSP seems to represent an unusual reaction of the body's immune system that is in response to this infection (either bacteria or virus).

• Aside from infection, drugs can also trigger the condition.
• HSP occurs most commonly in children, but people of all age groups can be affected, including adults.

The only known risk factors for HSP are exposure to certain viruses and drugs. The reaction to these agents that leads to HSP is not, however, predictable.

Classically, HSP causes a purple-appearing skin rash, pain in the abdomen, and joint inflammation (arthritis). Not all features need to be present for the diagnosis.

• The rash of skin lesions appears in gravity-dependent areas, such as the legs.
• The joints most frequently affected with pain and swelling are the ankles and the knees.
• Patients with HSP can develop a fever.
• Inflammation of the blood vessels in the kidneys (nephritis) can cause blood and/or protein in the urine.
• Abdominal pain and gastrointestinal bleeding are more common in children than in adults.
• Serious kidney complications are infrequent but can occur.

Symptoms usually last approximately a month. Recurrences are not frequent but do occur.

HSP is usually diagnosed based on the typical skin, joint, and kidney findings.

• Throat culture, urinalysis, and blood tests for inflammation and kidney function are used to suggest the diagnosis.
• A biopsy of the skin, and less commonly kidneys, can be used to demonstrate vasculitis.
• Special staining techniques (direct immunofluorescence) of the biopsy specimen can be used with microscopic examination to document antibody deposits of IgA in the blood vessels of involved tissue.

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, especially on the lower extremities.

The treatment of HSP is directed toward the most significant area of involvement.

• Joint pain can be relieved by anti-inflammatory medications such as aspirin or ibuprofen (Motrin).
• Some patients can require cortisone medications, such as prednisone or prednisolone, especially those with significant abdominal pain or kidney disease.
• With more severe kidney disease, involvement called glomerulonephritis or nephritis, cyclophosphamide (Cytoxan), azathioprine (Imuran), or mycophenolate mofetil (Cellcept) have been used to suppress the immune system.
• Infection, if present, can require antibiotics.

HSP can have complications, which generally occur more frequently in children than in adults. These complications include

• severe abdominal pain and
• gastrointestinal bleeding.
• Adults can have extended kidney problems.

The prognosis (outlook) 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 or an abnormal bowel folding called intussusception.
• Some patients have recurrences of symptoms, particularly skin rash, for months to a year after the onset of the illness.

HSP can be prevented only to the extent that one minimizes exposure to viruses and certain drugs that could cause the abnormal immune response. As it is impossible to know who will get HSP, it is not possible to actually prevent it.