The nipple concavity is due to both congenital and acquired factors: firstly, congenital factors are mostly considered as congenital dysplasia, which may occur during the fetal period, or during puberty when the breast is just starting to develop, which requires early detection and early intervention before adulthood. Secondly, in terms of acquired factors, on the one hand, during the developmental stage, the developing nipple is squeezed and sunken due to the small bra; on the other hand, it is considered to be a disease factor, mostly seen in breast cancer, as the spread of cancer cells will erode the ligament below the nipple during the whole cancer process, making the nipple pulled and sunken, mostly in unilateral breast lesions. Finally, once the nipple is sunken in, it is best to go to the hospital for a comprehensive examination and targeted stretching and treatment.