text: 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.
  Eosinophilic 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% eosinophil composition in total leukocyte count can be elevated to 60% in EGPA, 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 eosinophilic stage can last months or years, and its symptoms can disappear, only to return later.