<unk>  consists of three stages, but not all patients develop all three stages or progress from one stage to the next in the same order; whereas some patients may develop severe or life-threatening complications such as gastrointestinal involvement and heart disease, some patients are only mildly affected, e.g. with skin lesions and nasal polyps.<unk>  is consequently considered a highly variable condition in terms of its presentation and its course. Allergic stage The prodromal stage is characterized by allergy. Almost all patients experience asthma and/or allergic rhinitis, with more than 90% having a history of asthma that is either a new development, or the worsening of pre-existing asthma, which may require systemic corticosteroid treatment. On average, asthma develops from three to nine years before the other signs and symptoms. The allergic rhinitis may produce symptoms such as rhinorrhea and nasal obstruction, and the formation of nasal polyps that require surgical removal, often more than once. Sinusitis may also be present.<unk>  stage The second stage is characterized by an abnormally high level of eosinophils (a type of white blood cell) in the blood and tissues as a result of abnormal eosinophil proliferation, impaired eosinophil apoptosis, and increased toxicity due to eosinophil metabolic products. A normal 5%<unk> omposition in total leukocyte count can be elevated to 60% in<unk> , and this local accumulation of eosinophil is involved in the pathogenesis of asthma described in the allergic stage by initiating and maintaining immune responses in inflammation. The symptoms of hypereosinophilia depend on which part of the body is affected, but most often it affects the lungs and digestive tract. The signs and symptoms of hypereosinophilia may include weight loss, night sweats, asthma, cough, abdominal pain, and gastrointestinal bleeding. Fever and malaise are often present. The<unk>  stage can last months or years, and its symptoms can disappear, only to return later. Patients may experience the third stage simultaneously. Vasculitic stage The third and final stage, and hallmark of<unk> , is inflammation of the blood vessels, and the consequent reduction of blood flow to various organs and tissues. The damage done to the blood vessels can be explained by the overabundance of eosinophils that are produced and flowing throughout the vasculature of the body; eosinophil production, while essential for assisting inflammatory responses to infections and diseases, can lead to tissue damage when it is done in excess. Local and systemic symptoms become more widespread and are compounded by new symptoms from the vasculitis. Severe complications may arise. Blood clots may develop within the damaged arteries in severe cases, particularly in arteries of the abdominal region, which is followed by infarction and cell death, or slow atrophy. Many patients experience severe abdominal complaints; these are most often due to peritonitis and/or ulcerations and perforations of the gastrointestinal tract, but occasionally due to acalculous cholecystitis or granulomatous appendicitis. The most serious complication of the vasculitic stage is heart disease, which is the cause of nearly one-half of all deaths in patients with<unk> . Among heart disease-related deaths, the most usual cause is inflammation of the heart muscle caused by the high level of eosinophils, although some are deaths due to inflammation of the arteries that supply blood to the heart or pericardial tamponade. Kidney complications have been reported as being less common. Complications in the kidneys can include glomerulonephritis, which prevents the kidneys' ability to filter the blood, ultimately causing wastes to build up in the bloodstream.
Eosinophilic granulomatosis with polyangiitis
Eosinophilic esophagitis
Granulomatosis with polyangiitis
Microscopic polyangiitis
Nephrogenic systemic fibrosis
Thromboangiitis obliterans
IgA vasculitis
Systemic vasculitis