High-resolution imaging may be effective in differentiating palindromic rheumatism (PR) from new-onset rheumatoid arthritis (NORA), according to new research published in Annals of the Rheumatic Diseases.
An ultrasound (US) was performed to evaluate synovitis, tenosynovitis, and non-synovial extracapsular inflammation (ECI) during and between flares on untreated PR patients (n = 31), anticyclic citrullinated peptide (CCP) positive patients with musculoskeletal symptoms (CCP+ at risk) (n = 33), and patients with NORA (n = 24)
Among the PR cohort, ECI was frequent during flares (19/31, 61%); of the ECI group, 63% (12/19) presented ECI in the absence of synovitis. Seven of the total PR patients (23%) had synovitis (greyscale ≥ 1 and power Doppler ≥ 1) during flare. ECI occurred more frequently in the hands and wrists among the PR group than NORA and CCP+ at risk patients (65% vs 29 % vs 6%, P < 0.05). PR patients were significantly more likely to present ECI without synovitis than the NORA (42% vs 4%, respectively; P = 0.003) and CCP+ at risk cohorts (42% vs 6%, respectively; P = 0.0012). Of the PR patients, 26% (8/31) developed RA and presented a similar US phenotype to NORA at progression. MRI scans proved to be more effective in capturing synovitis and ECI than US, the researchers also noted.
The study authors concluded, “In patients presenting with new joint swelling, US may refine management by distinguishing relapsing from persistent arthritis.”