A 34-year-old woman has noticed a bloody discharge from the nipple of her left breast for the past 3 days. On physical examination, the skin of the breasts appears normal, and no masses are palpable. There is no axillary lymphadenopathy. She has regular menstrual cycles and is using oral contraceptives. Excisional biopsy is most likely to show which of the following lesions in her left breast?

Intraductal papillomas are usually solitary and smaller than 1 cm. They are located in large lactiferous sinuses or large ducts, and have a tendency to bleed, though they are benign. Abscesses complicating mastitis organize with a fibrous wall. Fibroadenomas contain ducts with stroma and are not highly vascular; these lesions are not located in ducts. Phyllodes tumors also arise from the intralobular stroma and can be malignant, but they do not invade ducts to cause bleeding. Sclerosing adenosis, a lesion occurring with fibrocystic changes, has abundant collagen, not vascularity.