What is allergic bronchopulmonary aspergillosis (ABPA)?
ABPA is a noninvasive form of pulmonary aspergillosis that occurs almost exclusively in asthmatics, usually younger than 40 years of age. Patients often will have peripheral eosinophilia and IgE specific antibodies against Aspergillus .
ABPA is the result of an IgE mediated hypersensitivity reaction to Aspergillus within the bronchial lumen. Repeated episodes of inflammation lead to bronchial wall breakdown and eventually bronchiectasis. Secretions, containing eosinophils and fungal hyphae, fill and can obstruct the affected airways.
This manifests radiographically as central and upper lobe predominant bronchiectasis, bronchial wall thickening, and mucoid impaction, findings that could mimic cystic fibrosis. The mucoid impactions on CT can sometimes have high attenuation, which is a suggestive sign of ABPA.