Case presentation: A 48-year-old man with a 75-pack-year history of tobacco use was referred to pulmonary clinic for evaluation of an abnormal chest roentgenograph. He had been followed by his primary physician for bronchitis and nonproductive cough over the past year and was recently treated with a course of antibiotics with no change in symptoms. He had no other medical history, was currently smoking two packs of cigarettes per day, and reported working on the docks in a shipyard for five years. On physical examination, he was afebrile with stable vital signs and 97% oxygen saturation on room air. He was well-developed in no apparent distress. On cardiovascular examination, he was in sinus rhythm without murmurs. Chest examination was clear to auscultation. There was no lymphadenopathy. The abdomen was soft and benign. The extremities were without clubbing, cyanosis, or edema. The rest of the physical examination was unremarkable.
Laboratory data: Laboratory data demonstrated a white blood cell count of 7,200/ul with a normal differential. Hemoglobin, platelet count, serum electrolytes, liver associated enzymes and coagulation studies were normal.
Imaging studies: The patient had a chest computed tomography (CT) available for review (Fig. 2). What diagnostic study should be performed next?