Background/Purpose: Palindromic rheumatism (PR) is defined as a recurrent, self-abortive arthritis and/or para-arthritis, which progresses to RA in up to 50% patients (pts), particularly those that are anti-CCP+(1). The anatomical basis for the palindromic flare is unclear and may provide insights into the initial phases of RA. We aimed to describe the ultrasound (US) and MRI phenotype of palindromic flare, focussing on intra- and peri-articular inflammation, as compared to early RA.       

Methods: Pts were recruited from a prospective PR cohort. Palindromic flares were defined as the presence of ≥2 of pain, swelling, erythema in or around ≥ 1 joint, that later returned to normal. Comprehensive blinded US assessment (wrists, MCPs, PIPs, elbows, knees, MTPs, bilateral ECU and 2^nd – 5^th finger flexor tendons) was performed during flares. Tenosynovitis (TSV), peri-tendinous oedema (PTO), peri-articular soft tissue inflammation and subcutaneous (s/c) oedema were reported at each joint region. MRI was performed on the most symptomatic region during flare. MRIs were RAMRIS scored and descriptively scored by a blinded experienced reader for TSV, PTO, peri-articular soft tissue inflammation and s/c oedema. The same information was collected in the early RA pts.

Results: Twenty one flares were captured in 15 PR pts and imaged by US (21) and MRI (9) between May 2015 and April 2016 and compared with US and MRI of 16 early RA pts. The mean age of PR pts was 47 years, 10/15 (67%) were anti-CCP+ and 5/15 (33%) anti-CCP-. 13/15 (87%) were DMARD naive. All 15 pts had US (1pt had 3 flares captured, 4 pts had 2, and the remainder had 1) and 8 pts had MRI (4 anti-CCP+, 4 anti-CCP-, 1 had 2 flares captured). On US 10/15 pts (67%) had peri-articular inflammation and/or s/c oedema, in 6 pts this was without synovitis or TSV. Grey scale synovitis was present in 9/15 pts (60%), TSV and/or PTO were present in 5/15 (33%) pts. Power Doppler (PD) synovitis was present in only 3/15 (20%) pts. No erosions were found. On MRI, synovitis was present in 7/8 pts (88%), bone marrow oedema (BME) in 1 (11%) and no erosions were found. US (table 1) and MRI (table 2) lesions are shown for all palindromic flares and early RA pts.

Conclusion: PR has a distinct phenotype with peri-articular soft tissue inflammation and s/c oedema common in PR flares and occurring independently of synovitis and TSV. Synovitis and TSV appear more prevalent on MRI in anti-CCP+ rather than anti-CCP- PR pts in whom s/c oedema seems a prominent finding. The low prevalence of PD synovitis, BME and erosions further distinguishes PR flares from the imaging phenotype in RA.       (1)Russell et al. J Rheum 2006  

Table 1.  

Table 2.