Differential Diagnosis for Swelling of the Thumb

• Single most likely diagnosis
  • Trauma (e.g., sprain, strain, or fracture): This is the most common cause of thumb swelling due to the thumb's frequent use and vulnerability to injury.
• Other Likely diagnoses
  • Infection (e.g., paronychia, felon): Bacterial or fungal infections can cause swelling, redness, and pain in the thumb.
  • Arthritis (e.g., osteoarthritis, rheumatoid arthritis): Various forms of arthritis can lead to thumb swelling, especially in older adults or those with a history of arthritis.
  • Gout: This form of arthritis can cause sudden, severe swelling and pain in the thumb, often accompanied by redness and warmth.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Septic arthritis: A bacterial infection within the joint, which can lead to severe damage and disability if not promptly treated.
  • Osteomyelitis: A bone infection that can cause swelling, pain, and redness in the thumb, potentially leading to serious complications if left untreated.
  • Compartment syndrome: A condition where increased pressure within the muscle compartments can lead to nerve and muscle damage, requiring urgent medical attention.
• Rare diagnoses
  • Tumor (e.g., giant cell tumor, osteochondroma): Although rare, tumors can cause swelling and pain in the thumb.
  • Sarcoidosis: A condition that can cause inflammation and swelling in various parts of the body, including the thumb.
  • Hemangioma: A benign vascular tumor that can cause swelling and discoloration in the thumb.