Bumps on the Outside of the Breast

A bump on the outside of your breast could be a lump that you can feel by touching your breast or a dermatological condition. Common causes of lumps are cysts, fibroid masses, or mastitis, but because a lump is also a sign of breast cancer, the Susan G. Komen Foundation recommends scheduling an appointment with a health care provider to rule out cancer or any other dangerous conditions 1. Bumps that are visible on the surface of the skin can be caused by contact dermatitis or heat rash and necessitate a visit to the dermatologist.

Cysts and Fibroid Masses

A cyst is a fluid mass that can appear anywhere on the body. Some women are prone to frequent visible cysts in their breasts, and they can become more common during certain times in the menstrual cycle. In some cases, your doctor may want to drain the cyst to ensure that there is no breast cancer if it’s difficult to tell a hard lump from the cyst. Fibroadenoma, or fibroid masses, are benign tumors in the breasts. Neither cysts or fibroid masses are cause for immediate concern, but if you feel something odd in your breast, the Breast Health Project recommends erring on the side of caution and consulting with a physician 3.


If you are breastfeeding, a visible lump in your breast can be caused by a blocked or engorged milk duct, two of the three causes of mastitis. In both of these cases, you will feel a hard lump in the upper portion of your breasts where the milk flows down into the breasts themselves. Blocked or engorged milk ducts happen when you do not empty your milk ducts completely while breastfeeding. To treat mastitis, continue breastfeeding, massage the affected area, and apply warm or cool packs, depending on what makes you feel better. Consult a physician if the infection is not relieved through self treatment.

Breast Cancer

The Susan G. Komen Foundation lists the most common signs of breast cancer as a lump or hard knot in the breast, sudden nipple discharge, a swelling or redness in the breast, or an itchy, scaly sore 1. If your breast feels or looks different, be sure to see your health care provider right away. To best prevent a dangerous case of breast cancer, avoid smoking and unhealthy habits, and conduct regular self exams. Talk to your physician, especially if you have a history of breast cancer in your family, about when you should begin regular mammograms.

Contact Dermatitis

If you have contact dermatitis on your breasts, you will notice redness, swelling or blistering of the skin, which can look like bumps or, in extreme cases, like scaling. According to the University of Maryland Medical Center, 80 percent of contact dermatitis is caused by an irritant to the skin. In the case of breast bumps, the culprit could be a certain soap, your laundry detergent, perfume or the fabric of your bra. The treatment that you need depends on your age and health, so thoroughly wash your skin, shirt and bra in a non-irritating soap and water, place a cold cloth on the affected area, and call a medical professional.

Heat Rash

According to the U.S. Centers for Disease Control, heat rash is typically caused when you sweat excessively during hot weather 2. Humidity can exacerbate the problem. If you have heat rash on your breasts, you will notice a cluster of small red bumps that may look like a pimple or a blister in the lower region or the skin fold below your breasts. To treat heat rash, keep your breasts and bra dry, using dusting powder if necessary, and try to spend some time in a cooler environment.