Airway obstruction Quiz: Ace Your Exams

A 65-year-old man presents to the clinic with a 3-day history of shortness of breath, hemoptysis, and fever of 38.9°C (102°F). The patient reports a history of unexplained weight loss of 7 kg (15.4 lbs) and progressive shortness of breath over the past 3 months. He was admitted to the hospital 1 month ago for a right lower lobe consolidation and was treated for bacterial pneumonia. Past medical history is significant for hypertension, and a 40-pack-year smoking history. Temperature is 38.7°C (101.7°F), blood pressure is 135/78 mmHg, pulse is 96/min, respiratory rate is 24/min, and oxygen saturation is 92% on room air. On physical examination, decreased breath sounds and crackles are noted over the right lung fields. Laboratory evaluation reveals leukocytosis with left shift and elevated CRP. Chest x-ray demonstrates a right lower lobe consolidation. Which of the following is most likely to reveal the underlying etiology of this patient’s condition?