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Crystalline disease may be the cause of arthritis in seronegative RA patients
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Musculoskeletal ultrasound revealed hyperechoic deposits associated with synovitis, which could explain the presence of arthritis in certain patients with seronegative rheumatoid arthritis, according to researchers.
The researchers retrospectively analyzed the clinical and ultrasound characteristics from 26 patients with seronegative rheumatoid arthritis (RA). By definition, rheumatoid factor and anti-citrullinated peptide antibodies were not present, and 62% met the American College of Rheumatology / European League Against Rheumatism 2010 criteria for RA. Median symptom duration was 1.4 years, and symptoms were most commonly present in metacarpophalangeal joints (65%).
Images from seven age-matched control patients (four with osteoarthritis, two with seropositive RA and one with seronegative RA) were also studied.
Only five patients were being treated with disease-modifying anti-rheumatic drugs at the time the ultrasound images were taken. X-rays showed only two patients had chondrocalcinosis, one of whom had erosion.
Ultrasound images included seven anatomic sites (ankle, elbow, foot, hand, knee, shoulder and wrist). All patients showed multiple hyperechoic densities consistent with ultrasound appearance of calcium pyrophosphate and were not typical of gout. Calcific deposits were associated with synovitis and were identified in joints, tendons and tendon sheaths. Control imaging revealed scattered calcifications in one patient with osteoarthritis.
Ninety percent of the patients had calcifications in both joints and tendons, which were most commonly round (79%) or punctate (45%) in joints, according to the researchers. In tendons, calcification patterns were more likely to be punctate (79%) or linear (42%). All three patterns were seen in 58% of patients. Evidence of bony erosion was seen in nine patients. No effusions were amenable to aspiration.
Elevated parathyroid hormone was seen in four of 10 patients in subsequent tests.
The researchers concluded that ultrasound may be beneficial when X-rays are unrevealing and no effusions amenable to aspiration are present. – by Shirley Pulawski
Reference:
Arvikar SL, et al. Paper #183. Presented at: American College of Rheumatology Annual Meeting. Nov. 14-19, 2014; Boston.
Disclosure: Arvikar reported an affiliation with the Arthritis Foundation.