Vasculitides Health Article

Causes

There is no single disease process that underlies all the childhood vasculitides. Various causes have been proposed for specific disorders.

• Henoch-Schönlein purpura. Although the ultimate cause of HSP was unknown as of 2004, the disease is preceded by an acute upper respiratory infection in at least half the children diagnosed with it. In other cases HSP appears to be triggered by an immune complex reaction to certain vaccines (most commonly vaccines for typhoid, measles, yellow fever, or cholera) or medications (most commonly penicillin, erythromycin, quinidine, or quinine). A characteristic finding in children diagnosed with HSP is higher levels of immunoglobulin A (IgA) in the blood and deposits of IgA on the walls of the child's blood vessels.
• Kawasaki disease. It is thought that an infectious organism of some kind is the cause of Kawasaki disease, although no specific virus or bacterium has been identified as of 2004. The disease has been linked to a variety of disease agents, including parvovirus B19, HIV infection, measles, influenza viruses, rotaviruses, adenoviruses, Klebsiella pneumoniae, and Mycoplasma pneumoniae. Some doctors think that genetic and immunologic factors are involved as well as an infectious organism.
• Infantile polyarteritis nodosa. As with Kawasaki disease, various infectious organisms have been proposed as the cause of IPAN, including hepatitis B virus, Epstein-Barr virus (EBV), various retroviruses, streptococci, and even a virus usually found in cats. None of these viruses or bacteria has been found in all patients with IPAN, however. Another theory is that IPAN is an immune complex disease, but its trigger had not been identified as of 2004.
• Takayasu arteritis. The cause of TA is unknown as of the early 2000s but may involve genetic factors, as the disease has been reported in identical twins.
• Wegener's granulomatosis. The cause of Wegener's granulomatosis was not known as of 2004. As with other childhood vasculitides, various disease organisms (including fungi as well as bacteria or viruses) have been suggested as the cause, but none have been definitely identified. A genetic cause seems unlikely, as it is unusual for two people in the same family to develop the disease.

Symptoms

The early symptoms of the childhood vasculitides are often difficult to distinguish from those of other illnesses. This section will focus on the symptoms specific to each disease.

• Henoch-Schönlein purpura (HSP). HSP is an acute but self-limited illness characterized by a low-grade fever (around 100.4°F[38°C]), purpura, joint pains (usually in the ankles and knees), abdominal pain, bleeding in the digestive tract, and inflammation of the kidneys. Boys with HSP often have inflammation of the testicles.
• Kawasaki disease. Kawasaki disease has three stages: an acute stage lasting about 11 days, characterized by a high fever (over 104°F [40°C]), strawberry tongue and cracked lips, conjunctivitis, involvement of the liver, kidneys, and digestive tract, and inflammation of the heart muscle; a subacute phase lasting about three weeks, characterized by irritability, loss of appetite, the peeling of skin from the finger tips, and the development (in about 20 percent of patients) of aneurysms in the coronary artery; and a convalescent phase marked by expansion of the aneurysms and possible heart attack. As of the early 2000s, Kawasaki disease is the leading cause of acquired heart problems for children in the developed countries.
• Infantile polyarteritis nodosa. The early symptoms of IPAN are nonspecific, usually including fever, loss of appetite, weight loss, and pain in the abdomen. The disease is most likely to affect the kidneys, heart, or liver. Depending on the organ(s) involved, the child may develop aneurysms in the arteries supplying the kidneys, kidney failure, aneurysms in the coronary artery, congestive heart failure, massive bleeding in the digestive tract, aneurysms in the arteries supplying the brain, and stroke. About half of patients with IPAN develop pains in the joints or skin rashes; boys frequently have pain in the testicles.
• Takayasu arteritis. Takayasu arteritis is a chronic inflammatory disorder that affects the aorta (the large artery that leaves the heart) and its major branches. Its early symptoms include fever, weight loss, and a general feeling of tiredness. The disease may not be diagnosed for months or even years, however. The inflammation of the aorta eventually leads either to the formation of aneurysms or the narrowing or complete blocking of the blood vessels. The patient may feel aching or pain in parts of the body affected by inadequate blood supply, such as aching in the legs while walking or cramping sensations in the abdomen after meals. In rare cases, the patient may suffer a heart attack or stroke. The patient may develop high blood pressure if the blood supply to the kidneys is affected. TA is sometimes called pulseless disease because the doctor may not be able to detect the pulse on one side of the patient's body. Another diagnostic clue is a significant difference (greater than 30 mm Hg) in the blood pressure on the right and left sides of the body.
• Wegener's granulomatosis. Wegener's most commonly affects the upper respiratory tract, the eyes, ears, kidneys, and skin. The disease is called a granulomatosis because it is characterized by the formation of granulomas, which are small lumps or nodules of inflammatory cells in the patient's tissues. The patient may have recurrent ear infections that are slow to heal, inflammation of the tissues inside the eye, inflamed sinuses, nosebleeds, coughing up blood, narrowing of the windpipe, and saddle nose, which is a deformity caused by the collapse of cartilage inside the nose. The patient may also have joint pains, loss of appetite, skin lesions, and fever. Vasculitis associated with Wegener's may lead to a heart attack. If untreated, the disease eventually progresses to kidney failure and death.