American Board of Family Medicine (ABFM) Practice Exam

What factor increases the likelihood of malignancy in a solitary pulmonary nodule?

1. Decreasing size over time

2. No calcifications

3. Absence of symptoms

4. Increasing size over time

The correct answer is: Increasing size over time

The factor that increases the likelihood of malignancy in a solitary pulmonary nodule is increasing size over time. Growth in size is a significant indicator that raises suspicion for lung cancer. Most malignant nodules tend to grow over time, so if a solitary nodule shows a measurable increase in size on follow-up imaging, it is more likely to be cancerous. In contrast, a nodule that decreases in size over time is often considered less likely to be malignant, as many benign processes may lead to resolution or reduction in size. Calcifications, especially when they have a characteristic pattern seen on imaging, can also indicate a benign etiology. Additionally, the presence or absence of symptoms can vary widely with both benign and malignant nodules, but a growing nodule is a clear red flag for malignancy. Thus, when evaluating solitary pulmonary nodules, longitudinal growth is one of the primary criteria that clinicians use to assess the risk of cancer.