A 26-year-old woman presents to the outpatient clinic with a painless lump in her left breast that she noticed six months ago. The lump has not changed in size, and she denies symptoms such as nipple discharge, skin changes, or breast pain. She has no significant medical history, is not on any medications, and has no family history of breast cancer. Which of the following clinical features is most characteristic of a breast fibroadenoma?
