Most lumps turn out to be fibrocystic changes. The term "fibrocystic" refers to fibrosis and cysts. Fibrosis is the formation of fibrous (or scar-like) tissue, and cysts are fluid-filled sacs. Fibrocystic changes can cause breast swelling and pain. This often happens just before a period is about to begin. Your breasts may feel nodular, or lumpy, and, sometimes, you may notice a clear or slightly cloudy nipple discharge.

Benign breast tumors such as fibroadenomas or intraductal papillomas are abnormal growths, but they are not cancer and cannot spread outside of the breast to other organs. They are not life threatening. Still, some benign breast conditions such as papillomas and atypical hyperplasia are important because women with these conditions have a higher risk of developing breast cancer.

Types of Breast Cancers
It is important to understand some of the key words used to describe different types of breast cancer. It is not unusual for a single breast tumor to be a combination of these types and to have a mixture of invasive and in situ cancer.

Adenocarcinoma: Nearly all breast cancers start in the ducts or lobules of the breast. Because this is glandular tissue, they are called adenocarcinomas, a term applied to cancers of glandular tissue anywhere in the body. The 2 main types of breast adenocarcinomas are ductal carcinomas and lobular carcinomas.

In situ: This term is used for the early stage of cancer, when it is confined to the immediate area where it began. Specifically in breast cancer, in situ means that the cancer remains confined to ducts (ductal carcinoma in situ) or lobules (lobular carcinoma in situ). It has not invaded surrounding tissues in the breast nor spread to other organs in the body.

Ductal carcinoma in situ (DCIS): Ductal carcinoma in situ (also known as intraductal carcinoma) is the most common type of noninvasive breast cancer. DCIS means that the cancer cells are inside the ducts but have not spread through the walls of the ducts into the surrounding breast tissue.