Hidden pain over the left breast is a common clinical cause of breast hyperplasia, herpes zoster, myocardial ischemia and so on. 1. Mammary gland hyperplasia: this condition refers to a benign breast disease caused by malfunctioning of the normal development and degeneration process of the mammary gland, with clinical manifestations of breast pain, nodules or lumps, and some of the affected people will also suffer from nipple discharge symptoms. 2. Herpes zoster: this condition refers to an infectious disease that affects the nerves and skin, which is caused by varicella zoster virus, with the onset of the disease in the chest, abdomen and limbs, etc. The clinical manifestations are blisters and papules in the affected area, accompanied by burning skin and pain on touch. 3. Myocardial ischemia: this is a clinically defined pathophysiological state, mainly caused by coronary artery stenosis, myocardial blood supply, insufficient oxygen supply, the main clinical manifestations of the affected people are discomfort and pain in the anterior region of the heart, and some of the people are accompanied by dyspnea, cardiac arrhythmia, and symptoms such as radiating pain in the left shoulder. In addition, breast cancer, breast fibroid, mastitis and breast trauma may also produce similar symptoms, and it is recommended that people with the disease should go to the hospital to complete the relevant examinations to determine the cause of the disease and carry out targeted treatment.