Vasculitides Health Article

Definition

Vasculitides is the plural of the word vasculitis, which may be used to describe any disorder characterized by inflammation of the blood or lymph vessels. Vasculitis is not a distinctive disease in its own right, but rather a symptom or characteristic of a number of different diseases. It can affect any type or size of blood vessel—large arteries and veins as well as arterioles, venules, or capillaries. The term juvenile vasculitides is sometimes used to refer to a group of disorders that primarily affect children and adolescents. These disorders vary widely in their severity as well as the specific blood vessels and organs affected. Some are mild and may resolve even without treatment, while others are potentially life-threatening. The most common childhood vasculitides are Kawasaki syndrome (sometimes called Kawasaki disease) and Henoch-Schönlein purpura.

The most widely used classification scheme for the vasculitides was first proposed at an international conference in 1994. It classifies these disorders according to the size of the blood vessels involved:

• Large-sized vessel vasculitis. This category includes two disorders, only one of which—Takayasu arteritis (TA)—is found in children and adolescents.
• Medium-sized vessel vasculitis. This category includes infantile polyarteritis nodosa (IPAN) and Kawasaki disease.
• Small-sized vessel vasculitis. The disorders in this category include Henoch-Schönlein purpura (HSP) and Wegener's granulomatosis.

Description

Vasculitis may damage blood vessels in two different ways. In some cases the inflamed tissue becomes weakened and stretches, producing a bulge in the wall of the vessel known as an aneurysm. The aneurysm may eventually rupture or burst, allowing blood to escape into nearby tissues. In other cases, the inflammation causes the blood vessel to narrow, sometimes to the point that blood can no longer flow through the vessel. When enough of the larger vessels supplying a specific organ or other part of the body are closed by inflammation, the tissue that is starved for blood may die. The area of dead tissue is called an infarction or infarct.

The early symptoms of vasculitis frequently include fever, weakness, loss of appetite, weight loss, tiring easily, pains in the muscles or joints, and swollen joints. Some of the childhood vasculitides affect the skin, producing rashes, ulcers, or reddish-purple spots known as purpura. Others affect the lungs, digestive tract, kidneys, liver, nervous system, eyes, or brain, resulting in symptoms ranging from pain in the abdomen, diarrhea, coughing, or high blood pressure to shortness of breath, visual disturbances, headache or fainting, and numbness in the limbs. The specific symptoms of the more common childhood vasculitides are described in more detail below.

Transmission

Some of the childhood vasculitides may be preceded and possibly triggered by infectious diseases. In addition, Kawasaki disease sometimes occurs in epidemics, such as those reported in Japan in 1979, 1982, and 1985. No epidemics, however, have been reported since 1985.

Demographics

Most vasculitides are relatively rare disorders; one source estimates that about 100,000 persons (including adults as well as children and adolescents) are hospitalized each year in the United States for treatment of vasculitis. Although this number is small compared to the number of those treated for cancer or diabetes, the vasculitides can nonetheless have a significant financial and emotional impact on the families of children diagnosed with them.

The demographics of specific childhood vasculitides are as follows:

• Henoch-Schönlein purpura (HSP). HSP most commonly affects children between the ages of three and 12 years. The sex ratio is about 1.5–2 males for every one female. The disease is more common in North America between November and January; it is estimated to affect 14 or 15 children per 100,000. About 50–60 percent of children with HSP were diagnosed with strep throat or another upper respiratory infection two to three weeks before the onset of the vasculitis.
• Kawasaki disease. Kawasaki disease affects between one and three children per 10,000 in the United States each year. It is much more common in Japan, striking one child per thousand below the age of five. In the United States, Kawasaki disease is more common among children of Japanese descent than among children from other racial or ethnic backgrounds. It is also more likely to affect African Americans than Caucasians. The sex ratio is about 1.5 males for every one female. Kawasaki disease is primarily a disease of younger children; the average age at onset is 18 months, with 80 percent of cases found in children younger than five years.
• Infantile polyarteritis nodosa (IPAN). IPAN is a rare disease, and is sometimes described as a severe variant of Kawasaki disease. The incidence of IPAN in the United States is uncertain as of the early 2000s, primarily because of disagreements among doctors about the classification of childhood vasculitides; the most common figure given is 0.7 cases per 100,000 children. The first known case of IPAN was reported in London in 1870, although polyarteritis nodosa in adults was first described in 1852. Like Kawasaki disease, IPAN is more common in children of Asian descent. The male to female ratio is not known for certain, but is thought to be about two to one.
• Takayasu arteritis (TA). TA, which was first described by a Japanese ophthalmologist in 1908, is primarily a disease of adolescent and young adult women, although it has been diagnosed in children as young as six months. TA is relatively rare, affecting about 2.6 individuals per million. In the United States it is most common in young women of Japanese descent, with a male to female ratio of one to eight. In India, however, TA is more commonly associated with tuberculosis, and the sex ratio is two females for every one male.
• Wegener's granulomatosis. Wegener's granulomatosis is also a rare disease, diagnosed in one to three individuals per 100,000, with only 3 percent of these cases found in people below 20 years of age. It is, however, one of the most serious vasculitides. The male to female ratio is two to one.