A 36-year-old man with a hard, movable lump in the right nipple and pain on pressure is considered to have gynecomastia, which is mainly caused by an imbalance in the ratio of estrogen to androgen for a variety of reasons. When gynecomastia is present, there will be hyperplasia of breast ducts and surrounding mesenchyme, which can cause unilateral breast or subareolar tissue enlargement, accompanied by localized swelling and pain or pressure pain. Long-term use of certain drugs such as spironolactone in the treatment of primary aldosteronism can lead to imbalance of the ratio of female to male and increase the level of estrogen, resulting in breast development. A small number of patients with testicular tumors, due to the secretion of chorionic gonadotropin, can cause feminization of male breasts, or breast hyperplasia caused by elevated estrogen levels under testosterone stimulation. Liver disease such as hepatitis, cirrhosis patients due to liver cell inactivation dysfunction, can also make estrogen elevated, breast hyperplasia. Male nipple pain hard lumps should also consider the tumor, inflammation and other causes, it is recommended to timely visit the hospital specialist, improve the breast ultrasound and other related examinations, a clear diagnosis, follow the doctor’s instructions for treatment.