They are called axillary nodes. If breast cancer cells reach the underarm lymph nodes, they can continue to grow, causing the nodes to swell. When cancer cells have reached these nodes, they are more likely to spread to other organs of the body as well. There are several types of breast tumors. These lumps are often caused by fibrocystic changes.
Cysts are fluid-filled sacs, and fibrosis refers to the forming of connective tissue or scar tissue.
Fibrocystic changes can cause breast swelling and pain. The breasts may feel lumpy and sometimes there is a clear or slightly cloudy nipple discharge. Benign breast tumors are abnormal growths, but they do not spread outside of the breast and they are not life threatening. Breast cancer, on the other hand, involves malignant tumors. It is confined to the ducts.