Which histologic pattern best describes the emphysematous change seen in chronic obstructive pulmonary disease?

• A. Eosinophilic infiltration of bronchial walls
• B. Uniform dilation of airspaces distal to the respiratory bronchiole
• C. Interstitial fibrosis
• D. Alveolar edema

Answer: (B)

Emphysema is defined by destruction of the walls of the small air sacs, leading to permanent enlargement of airspaces distal to the terminal bronchioles. On histology, this shows as dilation of the airspaces beyond the respiratory bronchioles due to loss of alveolar septa and walls, producing larger, more open spaces with little inflammatory change. That pattern—uniform enlargement of airspaces distal to the respiratory bronchiole—best matches the emphysematous change in COPD.

The other descriptions reflect different lung processes: eosinophilic infiltration of bronchial walls suggests allergic inflammation such as asthma; interstitial fibrosis refers to thickened and scarred lung interstitium; alveolar edema denotes fluid-filled alveolar spaces, not structural destruction of alveolar walls.