Which of the following is the PRIMARY pathological hallmark of emphysema in COPD?

Explanation

## Pathological Definition of Emphysema **Key Point:** Emphysema is defined as permanent enlargement of airspaces distal to the terminal bronchiole, accompanied by destruction of the alveolar walls and loss of elastic recoil. ### Structural Changes - Loss of alveolar septa and elastic fibres - Coalescence of adjacent alveoli creating larger air spaces - Reduction in surface area for gas exchange - Loss of radial traction on small airways → airway collapse during expiration ### Types of Emphysema | Type | Location | Association | Pathology | |------|----------|-------------|----------| | **Centrilobular** | Proximal alveoli of acinus (sparing distal) | Smoking | Selective destruction | | **Panlobular** | Entire acinus uniformly | Alpha-1 antitrypsin deficiency | Diffuse destruction | | **Paraseptal** | Distal alveoli near pleura/septa | Younger smokers | Focal involvement | **High-Yield:** The key distinguishing feature is **destruction of alveolar walls** — this differentiates emphysema from simple airway obstruction or bronchitis alone. **Clinical Pearl:** Emphysema causes irreversible loss of elastic recoil, leading to air trapping and the characteristic "pink puffer" phenotype (pursed-lip breathing, barrel chest). [cite:Robbins 10e Ch 15]