Infection: Mastitis usually occurs when bacteria enter the breast through a break in the skin of the nipple or through the opening to the milk ducts in the nipple. Once inside the tissue, the bacteria multiply and cause an infection.
Mastitis often occurs during breastfeeding. This is partly because it is easy for bacteria from the baby's mouth and mother's skin to enter the breast through the nipple. An infection may also occur if a woman's breast becomes too full of milk. This may happen if a mother misses a feeding or has not completely emptied the breast. When the breast is overfull, milk may leak into the breast tissue. As a result, the surrounding breast tissue is vulnerable to infection.
Bacteria may also enter the breast tissue through cracks, open sores, or cuts in the nipples of women who are not breastfeeding or men. In addition, mastitis may occur in people who have pierced nipples. This is because the holes in the skin allow bacteria to enter the nipples and cause infections.
Postmenopausal women may develop chronic mastitis as a result of their bodies' hormonal changes. The hormonal changes may cause the ducts below the nipple to become blocked with debris and dead skin cells. This causes swelling and makes the person vulnerable to bacterial infections.
Inflammatory breast cancer: Although uncommon, mastitis may also be caused by a rare form of cancer called inflammatory breast cancer. Inflammatory breast cancer occurs when cancer cells multiply inside the lymphatic vessels above the breast. These cells eventually clog the vessels, causing the breast to become red, swollen, and dimpled.
Infection: Testing is usually not generally needed to diagnose mastitis. Instead, a doctor typically diagnoses mastitis based on a physical examination. The doctor looks for characteristic signs of the condition, including a fever, chills, and a painful area in the breast.
During the examination, a doctor will also check to see if the patient has developed a collection of pus, called an abscess, in the breast tissue. This is a common complication that develops when mastitis is left untreated.
Inflammatory breast cancer: If inflammatory breast cancer is suspected, a biopsy is performed to determine if the patient has cancer. A small sample of the patient's breast tissue is analyzed in a laboratory for cancerous cells.
signs and symptoms
Infection: The breast is typically swollen and may feel warm and tender to the touch. Other symptoms may include pain or a burning sensation during breastfeeding, a general feeling of discomfort, reddening of the skin on the breast, and fever.
Inflammatory breast cancer: Patients with inflammatory breast cancer experience swelling in their breasts. Additional symptoms may include itching on the breast, pink or red-colored skin on the breast, ridges and thickened areas of skin on the breast, a bruise-like appearance on the breast, nipple retraction, nipple discharge (which may or may not be bloody), breast pain, change in color and texture of the areola, or the breast may be warm to the touch.
Abscess: If mastitis is not properly treated or it is related to a plugged milk duct (called milk stasis), a collection of pus (called an abscess) may develop in the breast tissue. An abscess usually feels like a small, hard lump in the breast. Patients with breast abscesses usually need to have the fluid surgically drained. Some research suggest that as many as 10% of women with mastitis develop abscesses. However, many experts consider this estimate to be very high.
Recurrence: Women who have had mastitis in the past are more likely to experience the condition again in the future.
Breastfeeding: Most cases of mastitis are caused by infections that happen during breastfeeding. This is partly because bacteria from the mother's skin or the baby's mouth can easily enter the breast through the nipple during feeding and cause an infection.
Breastfeeding mothers who wear nipple shields or shells, breast pads, or other breast-feeding aids have an even greater risk of developing mastitis. Although these aids help infants feed efficiently, they may block milk flow and increase germs on the nipple, increasing the chance of infection.
Wearing a tight-fitting bra during lactation also increases the risk because the bra may restrict milk flow.
Breastfeeding women who have sore or cracked nipples have an increased risk of developing mastitis.
History of mastitis: People who have had mastitis in the past are more likely to experience the condition again in the future.
Hormonal changes: Post-menopausal women have an increased risk of developing mastitis. This is because hormonal changes may cause the ducts below the nipple to become blocked with debris and dead skin cells. This causes swelling and makes the breast tissue vulnerable to bacterial infections.
Nipple piercings: Nipple piercings (in women or men) also increase the risk of developing mastitis.
Nipple sores: Men or women who have cracks, open sores, or cuts in their nipples have an increased risk of developing mastitis.
Inflammatory breast cancer
Age: The risk for inflammatory breast cancer increases with age.
Alcohol consumption: Drinking two or more alcoholic beverages a day appears to increase the risk of many types of cancer, including inflammatory breast cancer.
Hormonal therapy/birth control pills: People who take estrogen and progesterone, including birth control pills, appear to have an increased risk of developing inflammatory breast cancer.
Medical history: People who have had breast cancer or non-cancerous breast disease in the past have an increased risk of developing inflammatory breast cancer. In addition, people who have family histories of breast cancer have an increased risk of developing inflammatory breast cancer. This is because some cases have been linked to inherited genetic mutations.
Race: Caucasians are more likely to develop inflammatory breast cancer than the general population. This is because some cases have been linked to inherited genetic mutations.
Radiation therapy: People who have undergone radiation therapy on the breast or chest area have an increased risk of developing inflammatory breast cancer.