Mammary duct ectasia
Usually affecting women approaching menopause, mammary duct ectasia is a condition that occurs when the ducts beneath the nipple become swollen and can become blocked and usually improves without treatment.
It may feel like a small lump just under your nipple and can cause your nipple to feel tender or irritated, and may cause nipple discharge. In some cases, your nipple may retract (pull inwards).
Though it's normal to worry about changes in your breasts, mammary duct ectasia is not a symptom of breast cancer.