American Board of Internal Medicine (ABIM) Certification Practice Exam

What margin characteristic is associated with high risk solitary pulmonary nodules?

1. Smooth

2. Scalloped

3. Corona radiata or spiculated

4. Irregular

The correct answer is: Corona radiata or spiculated

High-risk solitary pulmonary nodules are often characterized by a spiculated or corona radiata margin. These features indicate a greater likelihood of malignancy compared to smoother, more well-defined nodules. The spiculated margin reflects the potential for tumor infiltration into surrounding tissues, making it a significant indicator on imaging studies such as CT scans. In contrast, a smooth margin suggests a lower likelihood of cancer, as benign lesions like hamartomas or infectious granulomas generally present in this way. Scalloped edges might also be seen in some benign processes or slow-growing tumors but are not as definitive as spiculated margins in suggesting malignancy. Irregular margins can suggest malignancy, but the presence of spiculated or corona radiata characteristics is more specifically associated with high-risk lesions. Therefore, the presence of spiculated or corona radiata margins creates the highest suspicion for a malignant process in solitary pulmonary nodules.