The most appropriate management is to discontinue further imaging. This patient was found to have a subcentimeter pulmonary nodule. The Fleischner criteria recommend surveillance with repeat chest imaging in a high-risk patient (history of smoking or other risk factors for lung cancer) at intervals based on the size of the nodule. For subcentimeter nodules at 6 mm, the recommendation is initial follow-up CT at 6 to 12 months and then at 18 to 24 months if no change. If imaging demonstrates stability of the nodule (and no other new findings) for 24 months, no further imaging is required.

Given the higher probability of malignancy with ground-glass opacification and partly solid nodules, patients with these types of tumors may warrant longer, if not life-long, surveillance. Patients with such nodules would benefit from a pulmonary consultation. This patient, however, has no evidence of associated ground-glass opacification and does not currently meet any other criteria for further imaging with a repeat CT, PET/CT, or chest radiograph.

Recent guidelines recommend screening with annual low-dose CT in patients with at least a 30-pack-year history of smoking who are currently smoking or quit within the last 15 years if the patient is between the ages of 55 and 80 years. This patient, however, quit smoking 20 years ago, so he does not meet criteria for screening.