American Board of Surgery Qualifying Exam (ABS QE) Practice Test

What distinguishes a hepatic hemangioma from other liver lesions in terms of contrast behavior?

1. Rapid washout

2. Hyperenhancement

3. Peripheral enhancement with retention

4. Isoattenuation

The correct answer is: Peripheral enhancement with retention

A hepatic hemangioma is characterized by its unique contrast behavior in imaging studies, particularly on CT or MRI. The defining feature is peripheral enhancement with retention. This occurs because hemangiomas are vascular lesions composed of clusters of blood vessels. When a contrast agent is administered, it preferentially fills the vascular spaces in the hemangioma, causing the peripheral rim to enhance notably. Over time, this enhancement pattern persists, as the contrast remains within the vascular space rather than being washed out, which is typical in many other types of liver lesions. In contrast, other liver lesions typically exhibit different behavior. For example, malignant tumors may demonstrate rapid washout of contrast due to their increased metabolic activity and disrupted vascular structures. Hyperenhancement is seen in certain lesions but usually refers to a uniform or early-phase enhancement followed by washout, unlike the stable peripheral enhancement of a hemangioma. Isoattenuation on imaging often suggests a lesion that blends in with liver parenchyma and does not specifically indicate the classic hemangioma pattern. Thus, the contrast behavior of hepatic hemangiomas—characterized by peripheral enhancement that retains contrast over time—is what sets them apart from other liver lesions.