A 27-year-old Irish adult with cystic fibrosis (CF; ΔF508/G551D genotype) was commenced on ivacaftor in January 2011. Ivacaftor addresses the underlying cause of CF in individuals with the G551D genotype by increasing chloride transport through cell surface CF transmembrane conductance regulator. Before this, he suffered two to three respiratory exacerbations per year, none requiring hospital admission. Sputum was positive for Staphylococcus aureus and Pseudomonas aeruginosa. After 2 years of treatment, the patientLs FEV1 increased from 79% predicted to 95% predicted, and he was completely free of respiratory exacerbations during this time.

A previous chest computed tomography scan (CT) in 2011 showed mild diffuse bilateral upper lobe bronchiectasis (Figure 1A, arrowhead), mild diffuse airway wall thickening (straight arrows) and diffuse mucus plugging (curved arrows). A follow-up chest CT in 2013 showed stabilization of bronchiectasis (Figure 1B, arrowhead), marked improvement in airway wall thickening (straight arrows), and extensive clearing of mucus plugging (curved arrows).