Differential Diagnosis for Lateral 1st MCP Pain and Tenderness with Limited ROM

• Single Most Likely Diagnosis
  • De Quervain's tenosynovitis: This condition, which affects the tendons on the thumb side of your wrist, is the most likely cause due to its specific location and symptoms matching the description provided. It leads to pain and tenderness, especially when forming a fist, grasping, or turning the wrist.
• Other Likely Diagnoses
  • Thumb carpometacarpal (CMC) joint arthritis: This condition can cause pain and limited range of motion (ROM) in the thumb, particularly affecting the 1st MCP joint. It's common, especially in women, and can lead to significant disability if not addressed.
  • Gamekeeper's thumb (skier's thumb): An injury to the ulnar collateral ligament of the thumb, which can cause pain and limited mobility, especially if the injury is acute and has led to instability of the MCP joint.
  • Radial styloid tenosynovitis: Inflammation of the tendon sheath surrounding the tendons that control thumb movement can cause pain and limited ROM, similar to De Quervain's but may have slightly different triggers and locations of pain.
• Do Not Miss Diagnoses
  • Infectious tenosynovitis: Although less common, an infection within the tendon sheath can present with similar symptoms but requires urgent medical attention to prevent serious complications, including tendon rupture or spread of infection.
  • Gout or pseudogout: These conditions can cause sudden, severe joint pain and swelling, including in the 1st MCP joint, and are critical to diagnose due to their potential for recurrent episodes and the need for specific treatment.
• Rare Diagnoses
  • Tumors (e.g., giant cell tumor of the tendon sheath): These are uncommon causes of chronic pain and swelling around the joints and tendons but are important to consider in cases where the diagnosis is unclear or the condition does not respond to typical treatments.
  • Sarcoidosis: A systemic disease that can cause inflammation in various parts of the body, including the joints and tendons, leading to pain and limited mobility. It's rare but can mimic other conditions, making diagnosis challenging.