Hypersensitivity angiitis is a disease that occurs due to hypersensitivity reaction usually by a drug or a foreign agent such as a virus or bacteria. It causes damage and inflammatory changes in the small blood vessels. This condition occurs when the offending substance initiates an immune response to produce antibodies against it. The complexes of antigen and antibodies may get attached within the vessel wall leading to various symptoms such as fever, skin rash, arthritis etc.
In majority of cases only the skin is affected. But sometimes there may be systemic manifestation involving gastrointestinal tract, joints and kidney.
Causes Of Hypersensitivity Angiitis
The exact mechanism of hypersensitivity angiitis remains obscure. There is deposition of an immune complex in the blood vessels. This immune complex consists of antibodies and antigen. This complex is formed due to reaction to certain drugs or by infection. The most common drugs that may give rise to hypersensitivity angiitis is antibiotics.
Infections that may trigger hypersensitivity angiitis are those caused by viruses and bacteria. Hepatitis B and C viral infection or streptococcus bacteria are the cause in most patients. Hypersensitivity angiitis is also seen in people suffering from certain inflammatory conditions such as systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease. In rare cases it can be associated with some cancers.
Men and women are equally affected with the condition. It is more common in adult population; children are usually not affected with the disease.
Hypersensitivity Angiitis Symptoms
Hypersensitivity angiitis mainly affects skin. But in some cases it may also affect internal organs such as the kidney and intestine or the joints. Thus the commonest is skin manifestation. Usually rash is noticed on the skin. There are small or large raised purple spots on the skin, mainly in the lower leg. Together with rash, there may be burning and itching sensation.
Involvement of joints can cause pain in joints and difficulty in joint mobility. Sometimes intestines are involved. If this occurs, patient may complain of cramps in abdomen with frequent diarrhea. Blood in urine is an indication of kidney involvement. In severe form it may cause irreversible damage to kidney leading to kidney failure.
Diagnosis And Treatment Of Hypersensitivity Angiitis
There is no specific test to determine hypersensitivity angiitis. However, from blood test it is possible to know the disease that is responsible for the condition. If a new drug has been introduced recently, it may be the cause for hypersensitivity angiitis. If there is skin rash, biopsy of skin is helpful to diagnose the condition.
Treatment of hypersensitivity angiitis depends on the underlying cause. For example if the cause is determined to be a drug, patient is advised to stop consumption of this drug. If the cause is suspected to be an infection, necessary treatment measures are taken to cure the infection. If the symptoms are severe, immunosuppressant drugs or corticosteroids may be necessary.