A hard lump under the male nipple hurts when pressed, which may be caused by breast hyperplasia, external impact, growth and development. 1. Breast hyperplasia: Male breast hyperplasia will cause symptoms of breast enlargement and pain when pressed. 2. Impact: After external impact on the breast, male breast may have localized pain and lumps. Patients can use safflower oil and other medicines to apply on the affected area to improve the swelling under doctor’s guidance. 3. Growth and development: Men who are in puberty may also experience hard breasts due to hormone level disorders in the body. Nipple hardness and pain caused by growth and development usually do not need to be treated, and will gradually ease with age. When men have the symptom of hard lumps underneath the nipple that hurt when pressed, they should also consider the causes of mastitis and breast tumors, etc. It is recommended that patients go to the hospital in time for treatment under the diagnosis of professional doctors.