D2.72 - Radiological heterogeneity and inflammatory phenotypes in allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is considered the most severe form of fungal-driven type-2 asthma. Patients show marked radiological heterogeneity, ranging from normal CT scans to extensive bronchiectasis and mucus plugging. Whether these structural abnormalities truly reflect ongoing inflammatory activity remains unknown.

Seventeen adults with severe asthma and confirmed ABPA were evaluated in a tertiary referral center. Structural ABPA (CT+) was defined by the presence of bronchiectasis, mucus plugging or high-attenuation mucus on chest CT. Patients without these findings were classified as CT−. Biomarkers of type-2 inflammation (total IgE and blood eosinophils), and annual exacerbations were compared between groups using the Mann–Whitney U test. 

Twelve patients were CT+ and five CT−. Despite striking radiological differences, systemic type-2 inflammation was similar between groups. Median total IgE was 1079 IU/mL in CT+ versus 980 IU/mL in CT− patients (p=0.23), and median blood eosinophil counts were 850 versus 800 cells/mm³ (p=0.63). Importantly, clinical burden was also comparable, with no difference in annual asthma exacerbation (median 1.5 vs 1.0; p=0.55).

In severe asthma complicated by ABPA, structural abnormalities on chest CT may not define a more inflamed or clinically unstable phenotype. Rather than reflecting ongoing type-2 immune activity, these radiological changes appear to represent cumulative and largely irreversible airway damage. Our results showing dissociation between imaging and biological activity may challenge current assumptions in ABPA assessment and suggest that biomarker-based, rather than imaging-based, phenotyping may be used to guide truly precision-based therapeutic decisions.