Henoch-Schönlein purpura is an inflammation of small blood vessels that causes them to leak, resulting in a rash.

While Henoch-Schönlein purpura (HSP) can affect anyone, children between the ages of 2 and 6 are most likely to develop it.

HSP's characteristic rash presents as small red dots on the skin, usually on the legs and buttocks, which changes from red to purple, and later to brown, before fading over the following 10 days. The rash is present in all cases of HSP.

Other accompanying symptoms can include abdominal pain, nausea and vomiting, arthritis, and blood in the urine. Kidney damage is the most common and most serious long-term complication. Although death from HSP is rare, kidney disease is the leading cause.

Some studies have shown an increased number of cases HSP during the cooler fall and winter months.

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Henoch-Schönlein purpura may affect children between the ages of 2 and 6.

The exact cause of HSP is not clear. It may be an abnormal immune system response to infection or an extreme allergic reaction. Other people may be genetically predisposed to developing HSP.

Possible causes of HSP include:

  • Immune system: A healthy immune system produces antibodies to combat bacteria and viruses. In cases of HSP, the antibodies attack the blood vessels instead, which causes inflammation, leakage, and a subsequent rash.
  • Allergic reaction: An extreme allergic reaction to certain foods may cause HSP.
  • Genetics: Although rare, HSP occurs in people within the same family, including in twins. This suggests that some cases of HSP may have a genetic cause, although there is no research to prove this.
  • Other associations: Certain drugs, bacteria, insect bites, viral infections, food, cold weather, and trauma may also cause HSP.

Symptoms can occur in any sequence, but the kidneys are usually affected by HSP later in the development of the disease. Symptoms of HSP usually begin suddenly. In rare cases, a person may require hospitalization.

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A rash is a symptom of HSP and occurs in all cases.
Image credit: Peter Rammstein, 2010

Symptoms of HSP include:

Rash

Leaking blood vessels in the skin cause a rash, which usually appears as small red or purple dots that begin to resemble bruises over time.

The rash usually occurs on the legs, arms, or buttocks. Later, it may spread to the chest, back and face. The appearance of the rash does not change, get lighter, or disappear when it is pressed. The rash is characteristic of HSP and occurs in all cases.

Gastrointestinal problems

HSP can cause vomiting and abdominal pain, and blood may appear in the stool. Abdominal cramps and pain are usually worse at night.

Arthritis

Pain and swelling may occur in the knee and ankle joints, but it can also occur in the elbows and wrists.

Kidney problems

Blood in the urine is an indication that HSP has affected the kidneys. Protein in the urine or high blood pressure can suggest more severe kidney problems.

Headaches

The HSP can affect the central nervous system, which can result in people experiencing headaches, convulsions, and seizures. It can also affect the brain's ability to gather and interpret information.

Other symptoms

Some boys and men with HSP experience swollen testicles.

There is no reliable test for HSP, and it may be confused with other forms of vascular inflammation. A doctor will instead look for a combination of symptoms that collectively point to an HSP diagnosis.

For example, a combination of symptoms, including a rash, abdominal pain, and arthritis, usually indicates the presence of HSP. Diagnosis of HSP is even more likely if there are antibody deposits on the skin.

The presence of blood or protein in the urine usually indicates a kidney problem and could point to the presence of HSP if a rash is also present.

The following clinical procedures and tests can help to confirm a suspected HSP diagnosis:

  • Skin biopsy: Skin tissue is gathered, usually under local anesthesia, and examined for evidence of antibodies.
  • Kidney biopsy: Imaging techniques are used to guide the biopsy needle into a kidney to collect a tissue sample.
  • Urinalysis: Doctors will evaluate the urine for the presence of blood (hematuria) or protein (proteinuria).

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Pain may be managed with NSAIDs, such as ibuprofen.

There is currently no cure for HSP, but in most cases, the symptoms will resolve without treatment.

A person may take steps to relieve and manage any joint pain, abdominal pain, or swelling they are experiencing.

Pain can be initially managed with non-steroidal anti-inflammatory drugs (NSAIDs). In some cases, prescription steroid drugs may help reduce swelling of the soft tissues.

If the kidneys are severely affected, then immunosuppressive medications may be prescribed. In rare cases, hospitalization may be required for abdominal pain, bleeding from the digestive tract, or kidney problems.

If an allergy is the cause of HSP, then the individual should try to avoid the triggering food or medication. If a streptococcal infection is present, then doctors may prescribe antibiotics.

People with HSP with advanced kidney disease and renal failure may benefit from the mechanical cleansing of the waste products from the blood. This is called hemodialysis.

While a kidney transplant has previously been necessary in severe cases, HSP can reoccur in a transplanted kidney.

Most people make a full recovery after HSP but recurrence can occur in up to a third of people.

While kidney damage affects only about 1 percent of children, about 40 percent of adults will experience kidney failure within 15 years of the HSP diagnosis.

Pregnant women with a history of HSP are more likely to experience high blood pressure and protein in the urine.