How does lesion mobility help differentiate benign from malignant masses?

How does lesion mobility help differentiate benign from malignant masses?

• A. Benign masses move slightly; malignant masses tend to be fixed
• B. Benign masses fixed; malignant masses move
• C. Mobility does not help differentiate
• D. Malignant masses move more

Answer: (A)

Mobility tells you how freely a lesion moves within the surrounding breast tissue. Benign masses, like fibroadenomas, are usually well circumscribed and not infiltrating adjacent structures, so they tend to glide or move slightly when the breast is moved or when you gently shift the transducer. In contrast, malignant lesions tend to invade and fix to surrounding tissues such as Cooper ligaments, fascia, or muscle, making them feel tethered and less mobile or fixed. This pattern—mobility for benign lesions being present but limited, and malignancies often being fixed—helps differentiate between the two. Keep in mind it’s one piece of the puzzle: some cancers can be mobile in early stages, and some benign lesions may appear less mobile depending on location, so mobility complements other imaging features rather than deciding alone.

Mobility tells you how freely a lesion moves within the surrounding breast tissue. Benign masses, like fibroadenomas, are usually well circumscribed and not infiltrating adjacent structures, so they tend to glide or move slightly when the breast is moved or when you gently shift the transducer. In contrast, malignant lesions tend to invade and fix to surrounding tissues such as Cooper ligaments, fascia, or muscle, making them feel tethered and less mobile or fixed. This pattern—mobility for benign lesions being present but limited, and malignancies often being fixed—helps differentiate between the two. Keep in mind it’s one piece of the puzzle: some cancers can be mobile in early stages, and some benign lesions may appear less mobile depending on location, so mobility complements other imaging features rather than deciding alone.