A tall, thin 21-year-old male reports increasing shortness of breath after activity, with neck swelling and crackles on palpation. Which diagnosis should be suspected?

• A. Pulmonary embolism
• B. Spontaneous pneumothorax
• C. Pernicious anemia
• D. Cardiomegaly

Answer: (B)

This presentation points to a spontaneous pneumothorax, especially in a tall, thin young man who develops sudden shortness of breath after activity. The neck swelling suggests venous distention or air tracking into soft tissues, and the palpable crackling sensation indicates subcutaneous emphysema from air escaping into the tissues. In someone this age and body type, rupture of apical blebs can allow air to enter the pleural space, causing lung collapse. If the air collection becomes large enough and shifts mediastinal structures, it can progress to a tension pneumothorax, which further elevates neck vein pressures and worsens breathing.

The other diagnoses don’t fit as well. Pernicious anemia would produce chronic symptoms like fatigue and pale appearance rather than acute dyspnea with subcutaneous air. Cardiomegaly is a long-standing enlargement that typically presents with congestive signs rather than sudden, tissue-level air leakage. A pulmonary embolism could cause sudden dyspnea but wouldn’t explain subcutaneous crepitus or the classic tall, thin patient profile in this context.

In summary, the scenario most strongly aligns with spontaneous pneumothorax due to rupture of apical blebs in a tall, thin young adult, with subcutaneous emphysema producing the palpable crepitus.