On breast ultrasound, a mass that is taller-than-wide is most suggestive of malignancy.

• A. Taller-than-wide
• B. Wider-than-tall
• C. Round with smooth margins
• D. Multiloculated appearance

Answer: (A)

The orientation of a breast mass on ultrasound is a strong clue to its behavior. A mass that is taller-than-wide, meaning its anteroposterior dimension is greater than its width on the transverse view, is more suspicious for malignancy. This pattern arises because malignant tumors tend to grow by invading across tissue planes, extending vertically through the breast tissue rather than expanding primarily along the plane of the skin. That vertical growth produces a lesion that appears taller rather than wide.

In contrast, benign processes often grow along the natural tissue planes, so they tend to be wider-than-tall, giving a parallel orientation to the skin. A round, smooth-margin lesion is typically benign, and a multiloculated appearance, while it can be seen in various conditions, is not as specific for cancer as a taller-than-wide configuration.