Differential Diagnosis for Moving Tendon on Hand, Not Tender

• Single most likely diagnosis
  • Tenosynovial cyst or ganglion cyst: This is a common condition where a lump forms on the tendon due to fluid accumulation, which can cause the tendon to appear moving. The fact that it's not tender supports this diagnosis, as these cysts are often painless.
• Other Likely diagnoses
  • Tendon subluxation: This condition occurs when a tendon slips out of its normal position, which can give the appearance of a moving tendon. It might not be tender if it's a chronic condition or if the subluxation is not causing significant irritation.
  • Extensor tenosynovitis: Although this condition involves inflammation of the tendon sheath and can cause tenderness, some cases might be mild or chronic, leading to minimal pain. The moving tendon could be due to the swelling and fluid accumulation around the tendon.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Infectious tenosynovitis: Although less likely if the area is not tender, an infectious cause could lead to serious complications, including abscess formation or spread of infection. It's crucial to consider this diagnosis, especially if there's any sign of infection or if the patient is immunocompromised.
  • Tendon rupture: A partial rupture might not be very painful, especially if it's a chronic condition. Missing this diagnosis could lead to further tendon damage and functional impairment.
• Rare diagnoses
  • Tumors (e.g., giant cell tumor of the tendon sheath): These are rare but could cause a moving tendon appearance due to the mass effect. They are usually slow-growing and might not be tender.
  • Congenital anomalies of the tendon: Some individuals might have anatomical variations that could give the appearance of a moving tendon. These are rare and often identified incidentally.