The external region of the upper chest of both men and women is covered by breast tissue. In females, this breast tissue expands and develops to accommodate mammary glands, which are necessary for milk production in pregnant woman. Normal hormonal fluctuations or abnormal infections or disease can cause male or female breasts to become swollen. If swelling persists or is accompanied by pain or abnormal skin masses, speak with your doctor for further evaluation and care.
Hormones
Women experience a normal menstrual cycle in which the hormones (estrogen and progesterone) within the body fluctuate. Increased estrogen production during the menstrual cycle causes the ducts within the breasts to swell and enlarge. High progesterone levels within a woman's body signal the milk glands (lobules) to grow. When these hormonal changes occur, a woman can experience swelling, enlargement, tenderness or pain within the breast tissue. As hormone levels stabilize, swelling within the breast tissue will decrease and the breasts will return to their normal size and shape.
Normal hormonal fluctuations can also cause a condition called fibrocystic breast disease---a noncancerous condition in which abnormal changes occur within the breast tissue. Such changes can include breast swelling, tenderness or discomfort.
Infection
Infection within the breast tissue can be caused by a bacterium called Staphylococcus aureus. This bacterium is able to infiltrate the breast tissue through damaged skin on the breast or through the nipple, according to the National Institutes of Health. This type of infection occurs most frequently in breastfeeding mothers. As a result of this infection, you can experience significant swelling of the breast tissue, which can cause tenderness, pain and abnormal lumps within the breasts. The application of heat to the affected breast tissue or antibiotic treatment may be necessary to resolve swelling within the breasts.
Cancer
Certain types of cancer within the breast can cause breast swelling to occur in some patients, health professionals at the National Cancer Institute (NCI) explain. Inflammatory breast cancer---a rare form of cancer that interferes with the function of lymph vessels in the breast skin---can cause severe breast swelling in patients with this condition. The NCI reports that approximately 1 to 5 percent of people who have breast cancer develop this specific type of inflammatory cancer. Additional breast symptoms associated with inflammatory breast cancer include redness, warmth, tenderness and pain. Other forms of breast cancer can also cause swelling, which alters the size or shape of breast tissue.
