Sometimes the nipple is concave, consider that it may be related to congenital development, nipple pulling and other factors. 1. Congenital development: Some people have congenital dysplasia of the nipple. For example, shortened milk ducts, nipple smooth muscle dysplasia, fibrotic contracture of the internal breast tissue, etc. may cause nipples to be sometimes concave. 2. The nipple is pulled: with mastitis, breast cancer and other diseases. Pathologic tissues may invade the ducts, ligaments, fascia and other parts of the breast, which can lead to contraction of these parts, and then pull the nipple. There are other clinical factors that may also cause the nipple to be concave at times. It is recommended to go to the breast surgery department of the hospital, and cooperate with the doctor to improve the ultrasound, molybdenum target and other related examinations, in order to clarify the cause of the disease.