American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the follow-up protocol for a subcentimeter solitary solid pulmonary nodule that is ≤4 mm with high pretest probability?

1. Follow-up CT at 1 month

2. Follow-up CT at 12 months

3. No follow-up needed

4. Immediate surgical evaluation

The correct answer is: Follow-up CT at 12 months

The recommended follow-up for a subcentimeter solitary solid pulmonary nodule that is ≤4 mm, particularly when there is a high pretest probability for lung cancer, is to conduct follow-up CT imaging at 12 months. This approach is grounded in the multidimensional assessment of such nodules, which considers factors like size, morphology, and the patient’s clinical context. In cases where the nodule is very small (≤4 mm) and especially if there's a high pretest probability of malignancy, a 12-month interval is appropriate. This is because smaller nodules have a significantly lower likelihood of being malignant, especially if they are not concerning in appearance. The rationale behind this time frame is to allow enough duration to observe any changes that might suggest growth, while also not overwhelming the patient with unnecessary imaging too frequently. More aggressive follow-up such as a CT scan at 1 month would be excessive for a nodule of this size, as significant changes in very small nodules often take longer to develop. Likewise, immediate surgical evaluation is reserved for larger, more suspicious nodules or in cases where there is a strong indication for an intervention based on other clinical findings. No follow-up might miss the opportunity to monitor for changes, which could lead