A 71-year-old man presented with a persistent dry cough that had been gradually worsening over the past 30 years. The cough was worse at night, especially while lying flat. He was treated with famotidine for gastroesophageal reflux disease (GERD) and completed a trial of albuterol, without improvement. After a two-week course of omeprazole, the patient perceived moderate improvement in his cough, but it persisted at night. The patient had no other gastrointestinal, cardiac, or respiratory symptoms. He did not have sick contacts, fever, chills, myalgias, headaches, chest pain, fatigue, rash, or dyspnea. He had a history of smoking, seasonal allergies, and eczema. He was not a current smoker.

On examination, the patient was afebrile and normotensive. He had a body mass index of 38 kg per m² (class 2 obesity) and an oxygen saturation of 92% on room air. He had normal respiratory effort but decreased aeration in the bilateral lung bases. The rest of the physical examination was unremarkable. Chest radiography and subsequent computed tomography (CT) were performed (Figure 1 and Figure 2).