Differential Diagnosis for Left Shoulder Pain

The following is a comprehensive differential diagnosis for left shoulder pain, categorized for clarity and emphasis on potential severity.

• Single Most Likely Diagnosis
  • Rotator Cuff Tendinitis: This condition is the most common cause of shoulder pain, resulting from inflammation of the tendons surrounding the shoulder joint. It is often related to overuse or repetitive strain injuries.
• Other Likely Diagnoses
  • Adhesive Capsulitis (Frozen Shoulder): Characterized by stiffness and pain in the shoulder joint, adhesive capsulitis can significantly limit mobility and is more common in individuals with diabetes or those who have experienced prolonged immobility of the shoulder.
  • Bursitis: Inflammation of the bursae, the fluid-filled sacs that cushion bones, tendons, and muscles near joints, can cause pain and swelling in the shoulder.
  • Labral Tears: Tears in the labrum, the cartilage that surrounds the socket of the shoulder joint, can cause pain and instability in the shoulder.
• Do Not Miss Diagnoses
  • Myocardial Infarction (Heart Attack): Although less common, left shoulder pain can be a referred pain from a myocardial infarction, especially if the pain is accompanied by other symptoms like chest pain, shortness of breath, or nausea.
  • Pulmonary Embolism: In rare cases, shoulder pain can be related to a pulmonary embolism, particularly if the pain is sharp and accompanied by difficulty breathing or chest pain.
  • Thoracic Outlet Syndrome: Compression of the nerves or blood vessels that pass into the thoracic outlet (the space between your collarbone and first rib) can cause shoulder pain, numbness, and weakness.
• Rare Diagnoses
  • Pancoast Tumor: A type of lung cancer located at the top of the lung, which can cause shoulder pain due to local invasion of the tumor into the brachial plexus or ribs.
  • Osteonecrosis of the Humeral Head: A condition where the blood supply to the bone tissue at the head of the humerus is interrupted, leading to bone death and potentially causing shoulder pain.
  • Infectious or Inflammatory Arthritis: Conditions like septic arthritis or rheumatoid arthritis can cause shoulder pain, although they are less common causes compared to other diagnoses listed here.

Each of these diagnoses has distinct clinical features and requires a thorough history, physical examination, and sometimes additional diagnostic tests for accurate identification and appropriate management.