Synovial Cysts

Over the past year, asymptomatic wartlike nodules had slowly developed on the fingers of both hands of a 57-year-old woman. During that time, she also had noticed increasing stiffness and pain in her hands in the evening. She had hypertension, which was treated with an angiotensin-converting enzyme inhibitor.

No drainage from the nodules was evident. Proximal and distal interphalangeal joint changes were noted, which were consistent with osteoarthritis.

The synovial fluid aspirated by a rheumatologist was characteristic of osteoarthritis, with a white blood cell count of 750/μL and high viscosity.

Erosive osteoarthritis nodules are basically synovial cysts that extend outside the joints. Synovial cysts should not be confused with Heberden or Bouchard nodes, which represent joint widening or deformity.

The patient was treated with oral methotrexate and corticosteroid injection into the cysts. At the 3-month follow-up visit, the nodules had not resolved; however, the treatment had alleviated the stiffness and pain in the patient’s hands, and no new nodules had appeared in the interim.