Identification of a distinct imaging phenotype may improve the management of palindromic rheumatism

Abstract

ObjectivesTo use high-resolution imaging to characterise palindromic rheumatism (PR) and to compare the imaging pattern observed to that seen in new-onset rheumatoid arthritis (NORA).MethodsUltrasound (US) assessment of synovitis, tenosynovitis and non-synovial extracapsular inflammation (ECI) was performed during and between flares in a prospective treatment-naive PR cohort. MRI of the flaring region was performed where possible. For comparison, the same US assessment was also performed in anticyclic citrullinated peptide (CCP) positive individuals with musculoskeletal symptoms (CCP+ at risk) and patients with NORA.ResultsThirty-one of 79 patients with PR recruited were assessed during a flare. A high frequency of ECI was identified on US; 19/31 (61%) of patients had ECI including 12/19 (63%) in whom ECI was identified in the absence of synovitis. Only 7/31 (23%) patients with PR had synovitis (greyscale ≥1 and power Doppler ≥1) during flare. In the hands/wrists, ECI was more prevalent in PR compared with NORA and CCP+ at risk (65% vs 29 % vs 6%, p<0.05). Furthermore, ECI without synovitis was specific for PR (42% PR vs 4% NORA (p=0.003) and 6% CCP+ at risk (p=0.0012)). Eleven PR flares were captured by MRI, which was more sensitive than US for synovitis and ECI. 8/31 (26%) patients with PR developed RA and had a similar US phenotype to NORA at progression.ConclusionPR has a distinct US pattern characterised by reversible ECI, often without synovitis. In patients presenting with new joint swelling, US may refine management by distinguishing relapsing from persistent arthritis.

Palindromic rheumatism as part of the rheumatoid arthritis continuum

“…Isolated extra-capsular inflammation appeared to distinguish PR from RA as this pattern was rarely seen in the RA patients. As may be expected, US inflammation was rarely seen in PR patients when they were not flaring (11).…”

“…In a cross-sectional analysis of a Spanish PR cohort, the frequency of anti-CCP antibodies was similar in PR compared with early RA patients (53% vs 55% respectively) (6). Other international PR cohorts report similarly high frequencies of anti-CCP positivity (between 46% and 68%) (7)(8)(9)(10)(11). A notable outlier is a recently described Taiwanese PR cohort where only 11/84 (13%) of patients were anti-CCP positive and 12/84 (14%) were RF positive (12).…”

“…High resolution imaging of treatment-naïve PR patients suggests a distinct disease process compared with RA; ultrasound indicates inflammation in PR is predominantly centred on extra-capsular rather than intra-articular targets (11). Extra-capsular inflammation (including tenosynovitis and peri-articular soft tissue inflammation) in the absence of synovitis was also identified in another US study of PR patients (26).…”

“…For this to be true, one would expect the pattern of joint inflammation in flares of PR to be similar to that seen in RA. However, a recent imaging study of treatment-naïve PR patients observed the opposite (11). PR flares were characterised by a high frequency of extracapsular inflammation on ultrasound (US); 61% of patients had this finding and interestingly in 63% of these cases there was no co-existent synovitis.…”

Response to: ‘Ultrasound findings in palindromic rheumatism’ by Sanmarti et al

“…We thank Sanmarti et al 1 for their interest in our recent paper in which we describe the distinct imaging phenotype of palindromic rheumatism (PR) 2. As the authors point out, we identified a high prevalence of ultrasound (US) extra-capsular inflammation in flares of PR, often without coexistent US synovitis.…”