This patient presents with findings suggestive of rheumatoid arthritis (RA). Anti-citrullinated protein (anti-CCP) antibodies are highly specific for RA.
RA is a systemic, symmetric, inflammatory arthritis. It classically presents with pain and stiffness, particularly of the hands. Symptoms are often worse in the morning and improve with use. The distal interphalangeal (DIP) joint is classically spared. Two autoantibodies that are frequently associated with RA include rheumatoid factor (RF) and anti-CCP. RF is more sensitive for the diagnosis of RA, while anti-CCP is more specific for the diagnosis. Additional laboratory findings include elevated ESR (not specific) and sometimes neutropenia.
Wasserman discusses the American College of Rheumatology's diagnostic criteria for RA. The diagnostic criteria requires the presence of at least one joint with definite clinical synovitis not better explained by another disease. If this requirement is met, a scoring system evaluates the probability of RA. Higher point values are assigned for increasing numbers of joints involved and for high serologic positivity for RF or anti-CCP.
Jilani et al. discuss the role of anti-CCP in RA. Early studies showed that anti-CCP antibodies predict an increased likelihood of developing severe disease. The presence of citrullinated proteins in synovial fluid is not specific for RA and can be seen in other causes of inflammation; however, the presence of antibodies to citrullinated proteins is highly specific for RA.
Figure A depicts proximal interphalangeal (PIP) joint swelling and metacarpophalangeal (MCP) joint swelling characteristic of early RA.
Answer 1: Anti-Smith antibodies can be seen in lupus.
Answer 2: Antihistone antibodies are seen in drug-induced lupus.
Answer 3: Anticentromere antibodies are seen in scleroderma.
Answer 4: When compared to anti-CCP antibodies, anti-IgG antibodies (rheumatoid factor) are more sensitive, but less specific, for diagnosing RA.
Wasserman AM1. Diagnosis and management of rheumatoid arthritis. Am Fam Physician. 2011 Dec 1;84(11):1245-52.
PMID:22150658 (Link to Abstract)
Jilani AA1, Mackworth-Young CG2. The role of citrullinated protein antibodies in predicting erosive disease in rheumatoid arthritis: a systematic literature review and meta-analysis. Int J Rheumatol. 2015;2015:728610. doi: 10.1155/2015/728610. Epub 2015 Mar 4.
PMID: 25821469 (Link to Abstract)