Which statement best describes a malignant lesion’s margin on ultrasound?

• A. Speculated margins are commonly associated with malignancy
• B. Smooth margins are commonly associated with malignancy
• C. Halo margins indicate malignancy
• D. Circumscribed margins indicate malignancy

Answer: (A)

Margin appearance on breast ultrasound is a key clue to malignancy. Speculated margins describe irregular, spiculated edges that extend from the lesion into surrounding breast tissue. These projections reflect tumor invasion into adjacent fat and the desmoplastic reaction the body often mounts to cancer, so the edge appears jagged or tentacle-like rather than smooth. This irregularity contrasts with benign processes, which typically show smooth, well-defined borders that suggest a contained lesion. A halo margin is a thin hyperechoic rim around a lesion and is more commonly seen with benign conditions such as fibroadenomas or inflammatory changes, not cancer. Likewise, a circumscribed margin indicates a well-defined border, again more typical of benign lesions. Therefore, the finding most suggestive of malignancy is the speculated, irregular margin.