Female breasts are made up of lobules (milk-producing glands) and ducts (tubes that carry milk to the surface of the nipple). Both are surrounded by glandular, fibrous (connective) and fatty tissue.
Most breast lumps aren’t cancerous. Usually, they are fluid-filled lumps (cysts) or a fibroadenomas, which are lumps made up of fibrous and glandular tissue. There are other forms of breast lumps that are also benign but may require a biopsy or removal such as papillomas (a wart-like growth inside the milk ducts) and sclerosing lesions of the breast (having extra tissue growth inside the breast lobules)