Figure 2

Airway pathology in inflammatory bowel disease (IBD)-related airway involvement. a, b) Tracheobronchial inflammation is in the form of a dense and florid mixed submucosal lymphoplasmacytic infiltrate within the airway wall, sometimes markedly reducing airway patency. The mucosa can be ulcerated (a) and the inflammatory infiltrate (including neutrophils and a few eosinophils) can be seen permeating and homing toward the airway mucosa (b). Bronchial glands may be damaged or destroyed (not shown). Inflammation may also involve c) the more distal airways or bronchioles (diameter of the airway lumen ∼1.8 x 1 mm) down to d) the smallest airways (showing at least six bronchioles involved) in the form of acute and chronic exquisitely broncho- or bronchiolocentric inflammation, while the vasculature is spared and uninvolved. Occasionally, there is e) purulent bronchiolitis (can also be seen in IBD-associated bronchiolitis obliterans-organising pneumonia) and/or f) purulent bronchiolar and tissue necrosis. g) In a few cases constrictive bronchiolitis and chronic obstruction to airflow develop as a late manifestation.