A 55-year-old postmenopausal female presents with a new mass in her right breast. She states that the mass has been there for about 3 months and has slowly grown in size. She first noticed it when she was taking a shower. The mass is not painful. She reports no nipple discharge, no nipple inversion, and no skin changes. She had her first menstrual period at age 11. Her only pregnancy was at age 35. Her mother and sister both had breast cancer. On physical examination, she has a 2 cm palpable, hard, ill-defined, immobile, non-tender mass in the upper outer quadrant of her right breast. There is no palpable axillary or supraclavicular adenopathy.