## Centrilobular Emphysema: Definition and Pathology **Key Point:** Centrilobular (centriacinar) emphysema is characterized by selective destruction of the **proximal respiratory bronchioles** while the **distal alveoli remain relatively preserved**. ### Anatomical Basis The respiratory bronchiole is the transitional zone between the terminal bronchiole and the alveolar duct. In centrilobular emphysema: - The central portion of the acinus (respiratory bronchioles) is destroyed - The peripheral alveoli remain intact - This creates an asymmetric pattern of destruction ### Clinical Association **High-Yield:** Centrilobular emphysema is **strongly associated with cigarette smoking** and is the predominant pattern seen in smokers. It typically affects the **upper lobes and apices** preferentially. ### Comparison with Panlobular Emphysema | Feature | Centrilobular | Panlobular | |---------|---------------|------------| | **Distribution** | Upper lobes, apices | Lower lobes, bases | | **Pattern** | Proximal acinus involved | Entire acinus involved | | **Primary cause** | Cigarette smoking | Alpha-1 antitrypsin deficiency | | **Age of onset** | Middle-aged smokers | Young adults (if genetic) | **Clinical Pearl:** The distinction is important because centrilobular emphysema in a smoker suggests smoking-related COPD, while panlobular emphysema in a young patient should raise suspicion for alpha-1 antitrypsin deficiency. [cite:Robbins 10e Ch 15]
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