Most breast lumps are not cancerous (benign). Still, some may need to be biopsied
(sampled and viewed under a microscope) to prove they are not cancer.
Fibrosis and cysts
Most lumps turn out to be caused by fibrosis and/or cysts, benign changes in the breast tissue that happen in many women at some time in their lives. (This is sometimes called fibrocystic changes and used to be called fibrocystic disease.) Fibrosis is the formation of scar-like (fibrous) tissue, and cysts are fluid-filled sacs. These conditions are most often diagnosed by a doctor based on symptoms, such as breast lumps, swelling, and tenderness or pain. These symptoms tend to be worse just before a woman's menstrual period is about to begin. Her breasts …show more content…
Fibroadenomas and intraductal papillomas
Benign breast tumors such as fibroadenomas or intraductal papillomas are abnormal growths, but they are not cancerous and do not spread outside the breast to other organs.
They are not life threatening.
Still, some benign breast conditions are important because women with these conditions have a higher risk of developing breast cancer. For more information see "What are the risk factors for breast cancer?" and our information on Non-cancerous Breast Conditions.
Types of breast cancers
Breast cancer can be separated into different types based on the way the cancer cells look under the microscope.
Most breast cancers are carcinomas, a type of cancer that starts in the cells (epithelial cells) that line organs and tissues like the breast. In fact, breast cancers are often a type of carcinoma called adenocarcinoma, which is carcinoma that starts in glandular tissue.
Other types of cancers can occur in the breast, too, such as sarcomas, which start in the cells of muscle, fat, or connective tissue.
In some cases a single breast tumor can be a combination of different types or be a mixture of invasive and in situ cancer. And in some rarer types of breast cancer,