In some women, fibrocystic changes along with many cysts and fibroadenomas can cause serious problems of swelling, pain, and tenderness. Milk cysts and infections, including abscesses, can occur in the breast but this is almost always among women who are breastfeeding or who have recently given birth. It is harmless and frequently cannot be felt. In some cases the only symptom is a watery, pink discharge from the nipple. Since a watery or bloody discharge can be seen in cases of breast cancer, this must be evaluated by your physician.
Cancer can cause a lump.
A microscopic examination of the fluid, as well as a mammogram, is recommended to check this possibility. Surgical removal is in most cases recommended. Sometimes an injury to the breast will cause a bruise large enough to appear as a lump. The lump is actually a collection of blood in the traumatized area. There may be significant swelling and tenderness, but this should slowly return to normal over a few days or weeks.