A 40-year-old man has had an increasing cough with hemoptysis for 2 weeks. He has never smoked and is in very good health. On physical examination, his temperature is 38.2deg C. A chest radiograph shows an area of consolidation in the right upper lobe. His condition improves with antibiotic therapy; however, the cough and hemoptysis persist for 2 more weeks. Chest CT scan now shows right upper lung atelectasis. Bronchoscopic examination shows a tan, circumscribed obstructive mass filling a right upper lobe bronchus. Which of the following neoplasms is most likely to produce these findings?