A 47-year-old woman who has not seen a physician in over 20 years presents with painful joints, fatigue, weakness, and what she describes as “hideously misshapen hands.” Family history is significant for type 1 diabetes. Physical examination reveals deformed hands and a 2-cm soft mass that that is mobile and tender to palpation in the left popliteal fossa.
Which of the following is the underlying pathophysiology of this popliteal fossa mass?a. Monosodium urate crystal deposition
Fluid production from inflamed synovium. This patient is presenting with signs and systemic symptoms consistent with rheumatoid arthritis (RA). The tender mass in the popliteal fossa is likely a Baker cyst, a benign swelling of the synovial bursa found behind the knee joint. Baker cysts are caused by excessive fluid production from the inflamed synovium that commonly occurs in rheumatoid arthritis, a systemic inflammatory disorder that primarily attacks synovial joints. (A) Urate crystal deposition is a finding in gout, but this would cause the knee to be painful, erythematous, and swollen. Furthermore, it would be highly unusual for the swelling seen in a gouty knee flare to be limited to the popliteal fossa. (B) Redundant bone growth would not be tender and soft on physical examination. Such bone growth can be seen as osteophytes in osteoarthritis. (C) Obstruction of lymphatic drainage causes lymphedema, which is highly unlikely to occur in the popliteal fossa.