Constrictive bronchiolitis

High power view of constrictive bronchiolitis in a patient with severe progressive airflow obstruction following toxic fume exposure. There is complete obliteration of the bronchiole by submucosal scarring. The surrounding alveolar spaces are spared. Pentachrome stain.

Bronchioles are distinguished from bronchi by a lack of glands and cartilage. Hematoxylin and eosin stain.