9-09: Allergic Bronchopulmonary Aspergillosis

ABPA is a pulmonary hypersensitivity disorder caused by allergy to fungal antigens that colonize the tracheobronchial tree—most commonly to antigens of Aspergillus species in individuals with atopic asthma or cystic fibrosis. Primary criteria for the diagnosis of ABPA include (1) a clinical history of asthma or cystic fibrosis; (2) elevated serum total IgE levels (greater than 1000 IU/mL); (3) immediate cutaneous hypersensitivity to Aspergillus antigens or elevated serum IgE levels specific to Aspergillus fumigatus; and (4) at least two of the following: (a) precipitating serum antibodies to Aspergillus antigen or elevated serum Aspergillus IgG by immunoassay, (b) pulmonary radiographic abnormalities consistent with ABPA, or (c) peripheral blood eosinophil count greater than 500 cells/mcL (0.5 × 10⁹/L). Radiographic abnormalities include transient opacities, mucoid impaction, and proximal or central bronchiectasis. High-dose corticosteroids (eg, prednisone 0.5–1 mg/kg orally per day) for at least 2 weeks with gradual taper is the treatment of choice. Patients with corticosteroid-dependent disease may benefit from itraconazole or voriconazole. Relapses are frequent. For those who have frequent exacerbations or are unable to wean off steroids, the use of biologic agents, such as anti-IgE (omalizumab), anti-IL-5 (mepolizumab, benralizumab), or anti-IL4 receptor (dupilumab), has been shown to improve outcomes. Bronchodilators (see Table 9–4) may also be helpful. Complications include hemoptysis, severe bronchiectasis, and pulmonary fibrosis.