Hi,
Milk ducts can become blocked and inflamed that could result in a condition called mammary duct ectasia, and a breast lump can appear under the nipple.
Even though it's normal to be concerned about a breast lump under the nipple, this condition is not a sign of breast cancer, and doesn't increase your risk of breast cancer.
Hormonal changes in the body, can cause mammary duct ectasia, as well as nicotine from smoking, which causes your milk ducts to widen and become inflamed.