Sudden enlargement of nipple can be seen in pathology, such as breast cancer, nipple inflammation, and also in physiology, such as female physiological period. 1. Pathological nipple enlargement: breast cancer: some breast cancer patients may have nipple enlargement, accompanied by nipple overflow, pain and other symptoms, and breast lumps can be touched by palpation. Inflammation of nipple: mostly seen in breastfeeding women, nipple enlargement, swelling, pain and fever may occur. 2. Physiological nipple enlargement: nipple enlargement may occur during physiological period, which may be accompanied by periodic breast swelling and pain, and the symptoms can be relieved after the physiological period, so there is no need to worry too much. In addition, sudden enlargement of nipples may also occur during pregnancy. Some of the causes of nipple enlargement are listed above. When nipple enlargement occurs, it is recommended to consult a doctor as soon as possible to find out the cause.