Shoulder pain is a complex condition and there are many diseases that can cause shoulder pain. 1. Factors other than the shoulder can cause shoulder pain, such as shoulder pain of visceral origin: apical lung tumor, subdiaphragmatic lesions (such as liver abscess, cholecystitis, gastric fundic pancreatic cancer invading the diaphragm, etc.), mediastinal lesions including heart disease. Neurogenic: such as stroke. (3) Cervical origin: cervical spondylosis can cause shoulder pain. 2.Systemic diseases can also cause shoulder pain: such as rheumatoid arthritis, rheumatoid arthritis, shoulder pain can be the first symptom or co-exist with other joint pain. 3.Shoulder pain caused by lesions in the shoulder itself, such as shoulder tumor, inflammation (septic arthritis, frozen shoulder, calcific tendonitis, etc.), injury (such as fracture, acromion impingement syndrome, rotator cuff tear, glenohumeral joint injury, biceps tendonitis or rupture, acromioclavicular joint injury and dislocation) and many other causes.