Pressing pain under the breast is mainly due to breast trauma, mastitis, cystic hyperplasia of the breast, breast cancer and herpes zoster. 1. Mammary gland trauma: the breast is subjected to extrusion, abrasion, needle puncture, scalding and other traumatic injuries resulting in local skin and subcutaneous tissue damage, can appear under the breast pressure pain. 2. Mastitis: because of nipple breakage, bacterial infection and other inflammatory lesions of the breast, inflammatory exudation increases, so it will be painful to press on the breast. 3. Breast cystic hyperplasia: excessive proliferation of breast glandular ducts and glandular epithelial tissues leads to the expansion of breast lobules and glandular ducts to form cysts, which can lead to the formation of breast lumps and slight hidden pain can occur. 4. Breast cancer: cancerous proliferation of breast epithelial cells causes breast lump formation, nipple discharge, breast pain and other symptoms. 5. Herpes zoster: Breast skin herpes zoster will appear as a long skin papule in the breast area, accompanied by pain, and occasionally the patient will be self-conscious of the symptoms of itching. Breast swelling and pain may be related to a variety of factors, it is recommended to consult a doctor to clarify the diagnosis.