Inverted nipples are nipples that sink into the areola. The areola is the area around the nipple where the skin pigment is darker. In normal nipples, the nipple is above the areola surface so that the milk ducts inside the nipple are open and the milk secreted by the mammary glands can be discharged smoothly. In the case of nipple invagination, the end of the milk ducts and the opening of the milk ducts are trapped in the skin, which leads to inaccessible milk ducts and milk accumulation, which can easily lead to bacterial growth and the possibility of other diseases such as mastitis. Most of the nipple inversions are due to congenital developmental abnormalities, but some are due to trauma, inflammation or tumors. If the nipple inversions did not exist before, but suddenly found to appear, it cannot be ruled out that it is due to tumor infiltration around the nipple, causing the nipple skin to receive adhesions and tugging, so you should go to a regular hospital for general surgery or breast surgery as soon as possible to check and clarify the cause before dealing with it.