Differential Diagnosis for Left Shoulder Pain

The patient presents with intermittent left shoulder pain that worsens with certain movements, feels like a pinched nerve, and is not directly at the joint. The pain has been partially managed with medication for swelling but persists. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Subacromial Bursitis or Rotator Cuff Tendinitis: These conditions are common causes of shoulder pain, especially when it's related to movement and feels like a pinched nerve. The pain is often located in the shoulder region but not directly in the joint, consistent with the patient's description.

• Other Likely Diagnoses

  • Adhesive Capsulitis (Frozen Shoulder): Although it typically presents with more restricted movement and pain at the joint, some patients might experience pain in a manner similar to a pinched nerve, especially in the early stages.
  • Thoracic Outlet Syndrome: This condition involves compression of the nerves and/or blood vessels that pass into the thoracic outlet (the space between your collarbone and first rib). It can cause shoulder pain that feels like a pinched nerve, especially with certain movements.
  • Cervical Radiculopathy: Pain from the neck (cervical spine) can radiate to the shoulder, feeling like a pinched nerve. Certain movements can exacerbate this pain.

• Do Not Miss Diagnoses

  • Pancoast Tumor: A type of lung cancer located at the top of the lung that can cause shoulder pain due to invasion of the brachial plexus (nerves) or other structures. It's crucial to consider this, although it's less likely, due to its severe implications.
  • Spinal Cord Injury or Compression: Although less common, any condition affecting the spinal cord, such as a herniated disk or spinal stenosis, can cause radiating pain to the shoulder and must be ruled out due to the potential for serious neurological consequences.

• Rare Diagnoses

  • Polymyalgia Rheumatica: An inflammatory condition that affects the muscles, leading to stiffness and pain, typically in the shoulder and hip areas. It's less common but should be considered, especially in older adults.
  • Referred Pain from Abdominal or Cardiac Issues: In some cases, pain from the abdomen (like gallbladder disease) or heart (like myocardial infarction) can refer to the shoulder. These are critical to identify due to their potential severity, although they might not directly cause "pinched nerve" pain.

Each diagnosis should be considered in the context of a thorough patient history, physical examination, and potentially, diagnostic imaging or other tests to determine the underlying cause of the shoulder pain.