The most common cause of bronchiectasis is

The most common cause of bronchiectasis is

• A. Cigarette smoking
• B. Air pollution
• C. α1-Antitrypsin deficiency
• D. Recurrent bronchial infections

Answer: (D)

The concept being tested is that structural damage from repeated infections drives bronchiectasis. Bronchiectasis is permanent dilation of the bronchi caused by chronic inflammation and necrotizing infection that destroys the elastic and muscular components of the airway walls. When infections recur, neutrophils flood the airways and release proteases such as elastase, breaking down supporting tissue. This weakens the bronchial wall and allows it to dilate. The damaged epithelium and impaired ciliary clearance then trap mucus, creating a niche for further infections and a vicious cycle of inflammation and dilation. Because repeated bronchial infections are the leading pathologic trigger for this process, they are the most common cause. Cigarette smoking is a major risk factor for chronic bronchitis and COPD but not the primary driver of bronchial wall destruction seen in bronchiectasis. Air pollution can contribute but is not the most common cause. Alpha-1 antitrypsin deficiency mainly causes emphysema rather than bronchiectasis, though some patients with deficiency can have bronchiectasis secondary to repeated infections.

The concept being tested is that structural damage from repeated infections drives bronchiectasis. Bronchiectasis is permanent dilation of the bronchi caused by chronic inflammation and necrotizing infection that destroys the elastic and muscular components of the airway walls. When infections recur, neutrophils flood the airways and release proteases such as elastase, breaking down supporting tissue. This weakens the bronchial wall and allows it to dilate. The damaged epithelium and impaired ciliary clearance then trap mucus, creating a niche for further infections and a vicious cycle of inflammation and dilation. Because repeated bronchial infections are the leading pathologic trigger for this process, they are the most common cause.

Cigarette smoking is a major risk factor for chronic bronchitis and COPD but not the primary driver of bronchial wall destruction seen in bronchiectasis. Air pollution can contribute but is not the most common cause. Alpha-1 antitrypsin deficiency mainly causes emphysema rather than bronchiectasis, though some patients with deficiency can have bronchiectasis secondary to repeated infections.