Male left nipple below the muscle hidden discomfort, may be male breast hyperplasia, neuromuscular pain and other factors, it is recommended that patients go to the hospital in a timely manner to take a chest X-ray, to identify the cause of the disease and then symptomatic treatment. 1. Male breast enlargement: the main reason is the body’s estrogen and androgen ratio imbalance, male left nipple under the muscle hidden discomfort may be caused by male breast enlargement. The main manifestation of male breast enlargement, often unilateral onset, bilateral may also occur, accompanied by symptoms of tenderness. 2. Neuromuscular pain: usually caused by cold or inadvertent strain, can appear male left nipple muscle discomfort, may also be accompanied by pain symptoms; may also be chondromalacia, intercostal neuralgia and so on. In addition, male left nipple muscle discomfort may also be cardiothoracic diseases, tumors, inflammation and other causes, it is recommended that the patient timely medical examination, in order to clarify the cause, and comply with the doctor’s instructions. In daily life should pay more attention to rest, quit smoking and alcohol, appropriate sports.