A lesion described as wider-than-tall on ultrasound is most consistent with which diagnosis?

• A. Benign lesion such as fibroadenoma
• B. Malignancy
• C. Infection
• D. Fat necrosis

Answer: (A)

On ultrasound, the direction a lesion grows relative to the skin and chest wall provides a clue about benign versus malignant behavior. A lesion that is wider than it is tall tends to grow along the plane of the breast tissue rather than invading through tissue planes. This parallel, horizontal growth pattern is characteristic of many benign lesions, especially fibroadenomas, which often appear as well-defined, oval, homogeneous, and hypoechoic masses with a width greater than their height.

Malignant tumors, in contrast, more commonly show a taller-than-wide orientation because they tend to invade across tissue planes and grow vertically. While infections or fat necrosis can have varied appearances, the simple wider-than-tall orientation is best aligned with a benign diagnosis like a fibroadenoma in this scenario.