Differential Diagnosis for Arm Pain

• Single most likely diagnosis
  • Musculoskeletal strain: This is the most common cause of arm pain, often resulting from overuse, injury, or poor posture. Justification: High prevalence and common presentation in clinical practice.
• Other Likely diagnoses
  • Tendinitis: Inflammation of the tendons, often due to repetitive motion or overuse, leading to pain and stiffness in the arm. Justification: Common in individuals with repetitive jobs or activities.
  • Radiculopathy: Nerve root compression or irritation, causing pain that radiates down the arm. Justification: Frequently seen in patients with neck problems or those who have experienced trauma.
  • Bursitis: Inflammation of the fluid-filled sacs (bursae) that cushion joints, leading to pain and swelling. Justification: Often associated with repetitive motion or direct trauma to the affected area.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Acute arterial occlusion: Sudden blockage of an artery, leading to severe arm pain, numbness, and potentially gangrene if not promptly treated. Justification: Although rare, it is a medical emergency requiring immediate intervention.
  • Compartment syndrome: Increased pressure within a muscle compartment, causing pain, numbness, and potentially permanent damage if not treated promptly. Justification: Can result from trauma or intense physical activity, and delayed diagnosis can lead to serious complications.
  • Pulmonary embolism (if pain is referred): Although less common, arm pain can be referred from a pulmonary embolism, especially if it involves the upper lobes of the lung. Justification: A life-threatening condition that requires immediate diagnosis and treatment.
• Rare diagnoses
  • Thoracic outlet syndrome: Compression of the nerves and/or blood vessels that pass through the thoracic outlet, leading to arm pain and other symptoms. Justification: Less common but can be debilitating if not properly managed.
  • Complex regional pain syndrome (CRPS): A chronic pain condition characterized by severe, burning pain in the arm, often following an injury. Justification: Rare and challenging to diagnose, but important to consider in patients with persistent, unexplained arm pain.
  • Pancoast tumor: A type of lung cancer that can cause arm pain due to invasion of the brachial plexus. Justification: Rare but serious, highlighting the importance of a thorough diagnostic workup in patients with unexplained arm pain.