Left shoulder blade pain can be caused by shoulder diseases, cervical spine diseases, heart diseases and lung diseases. 1. Shoulder diseases: the most common causes include frozen shoulder, rotator cuff injury, periarticular synovitis, trauma and other shoulder diseases, which can cause bone and soft tissue injury at the left scapula, or localized aseptic inflammation, and stimulation by inflammatory substances can cause pain symptoms. 2. Cervical spine disease: cervical intervertebral disc herniation can lead to local nerve compression, causing pain and numbness in the left scapula. When a tumor occurs in the cervical spine, due to the compression of the tumor, pain symptoms may appear in the left shoulder blade. 3. Heart disease: angina pectoris, myocardial infarction and other heart diseases can be caused by myocardial ischemia, resulting in radiating pain in the left scapula and other parts of the left shoulder blade, accompanied by chest tightness, shortness of breath and other manifestations. 4. Lung diseases: when inflammation or tumor occurs in the left lung, or pleurisy occurs, pain symptoms may appear in the left shoulder blade and the left back and other areas. When left scapula pain occurs, you should consult a doctor in time and take appropriate treatment under the guidance of a specialized doctor, which can help to relieve the uncomfortable symptoms as soon as possible.