A 28-year-old previously healthy man presents with acute-onset right-sided chest pain and dyspnea. Chest X-ray confirms pneumothorax. What is the most common cause of spontaneous pneumothorax in this clinical scenario?
A. Cystic fibrosis with bronchiectasis
B. Rupture of apical blebs or bullae
C. Tuberculosis with cavitation
D. Marfan syndrome with connective tissue weakness
Explanation
Most Common Cause of Spontaneous Pneumothorax
Epidemiology & Pathophysiology
Key Point
Rupture of apical subpleural blebs or bullae is the most common cause of primary spontaneous pneumothorax (PSP) in young, tall, lean males.
Blebs are small air-filled cavities in the visceral pleura, typically located at the lung apex
They form due to alveolar rupture and air dissection along bronchovascular sheaths
Rupture allows air to escape into the pleural space
PSP accounts for ~75% of all spontaneous pneumothorax cases
Radiological Findings
Table
Feature
Appearance
Visceral pleural line
Thin, sharp line parallel to chest wall; no lung markings lateral to it
Location
Typically apical and anterior (upper lobes)
Lung collapse
Variable; depends on size
Associated findings
Blebs/bullae may be visible on CT; often not seen on plain film
High-Yield Facts
High-YieldNEET PG
Primary spontaneous pneumothorax (PSP) occurs without underlying lung disease; secondary pneumothorax occurs in patients with pre-existing pulmonary pathology (COPD, TB, CF, cystic lung disease).
Mnemonic: COPD-TB-CF — Common causes of secondary pneumothorax:
COPD (bullae rupture)
Tuberculosis (cavitary disease)
Cystic Fibrosis (bronchiectasis, cyst rupture)
Clinical Pearl
Clinical Pearl
Young, tall, lean males (especially smokers) are at highest risk for PSP. The male-to-female ratio is approximately 6:1. Smoking increases risk 20-fold.
Imaging Strategy
Chest X-ray: First-line; shows visceral pleural line and absent lung markings in the pneumothorax zone
CT chest: More sensitive for detecting small pneumothorax and identifying blebs/bullae; useful if diagnosis is uncertain or for pre-operative planning
Ultrasound: "Barcode sign" (absence of normal pleural sliding) is highly sensitive
Harrison 21e Ch 257
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