How is enlargement of the synovial membrane noted on physical exam in rheumatoid arthritis (RA)?

Updated: Feb 07, 2020
  • Author: Howard R Smith, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

In RA, enlargement of the synovial membrane is noted on physical examination as thickening of the synovium that may obscure joint margins. This thickening is most evident in the small joints of the hands and feet. In the MCP and MTP joints, the outline of the base of the proximal phalanx may become indistinct, and in the PIP joints of the fingers, a fusiform swelling is noted that is due to the anatomy of the synovial reflections (see the image below).

Rheumatoid arthritis. Soft-tissue swelling and ear Rheumatoid arthritis. Soft-tissue swelling and early erosions in the proximal interphalangeal joints in a patient with rheumatoid arthritis of the hands.

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