A 23-year-old woman presents with a painless lump in her right breast. She discovered the lump a few days ago, when doing a breast self-examination. She has no other symptoms. There is no history of trauma to the breast, or of previous breast lumps.

Her medical and surgical histories are unremarkable. She is not on any medications. Her family history is also unremarkable. She is nulliparous. Her menarche was at the age of 13 and her menstrual cycles are regular, with a 28-day duration. She is not on contraceptives currently.