A 66-year-old, male patient with a 10-pack-year history of smoking was referred to the internal medicine consultation because of a 4-week history of fatigue, weakness, intermittent low-grade fever, appetite and weight loss, and a mild dry cough. His previous history was unremarkable and his physical examination was normal. Routine laboratory screening revealed leukocytosis (11.08×109 leukocytes per L), elevated C-reactive protein (72.1 mg·L-1) and erythrocyte sedimentation rate 57 mm·h-1. Analyses for rheumatoid factor, antinuclear antibodies, and cytoplasmic and perinuclear anti-neutrophil cytoplasmic antibodies were all negative. Pulmonary function tests (static and dynamic volumes, flow–volume curve, and lung diffusion capacity) were within the predictive values. Chest radiography demonstrated bilateral hilar enlargement. The patient subsequently underwent a computed tomography (CT) scan of the chest (figure 1).