Because the word shoulder is used loosely by most patients, the location of a shoulder pain generally needs to be specified more exactly by the physician. He must next determine whether the cause is local or remote. A case history illustrates the puzzling results of repeated examinations of a painful shoulder in a woman who proved to have adenocarcinoma of the lung. Another patient, whose illness was ushered in by pain in the left forearm and hand, was found to have an intrathoracic tumor with partial destruction of two thoracic vertebrae. In the author's experience an extremely important common cause of shoulder pain is pulmonary infarction involving the diaphragmatic surface of the lung, but a variety of possibilities must be considered, including cardiovascular, intraabdominal, and even genitourinary disease. The laterality of the pain must be kept in mind, and pain in the right scapular region, for example, suggests biliary disease. When disease is intrinsic in the shoulder, the pain is commonly felt in the deltoid region, where pain of visceral origin rarely appears.
Morgan EH. PAIN IN THE SHOULDER AND UPPER EXTREMITYVISCERAL CAUSES CONSIDERED BY THE INTERNIST. JAMA. 1959;169(8):804-808. doi:10.1001/jama.1959.03000250022007