Background Palindromic rheumatism (PR) is an intermittent arthritis that may evolve to rheumatoid arthritis (RA), especially in patients with anti-citrullinated protein antibodies (ACPA), although significant numbers of patients do not evolve to RA after several years of follow-up. It is not known whether patients may have subclinical synovitis during the intercritical phase of the disease and whether this is a risk factor for progression to RA.
Objectives To analyze the presence of subclinical synovitis (measured by power Doppler ultrasound) in patients with pure PR in the asymptomatic phase and compare ultrasound (US) findings in ACPA (+) and ACPA (-) patients.
Methods Patients diagnosed with pure PR that had not progressed to chronic rheumatic disease at the time of the study were included. Clinical, demographic, serological and therapeutic variables were collected. US assessment of both hands, including the wrists, metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints, and the flexor and extensor tendons of the wrists and hands was performed in all patients during the asymptomatic disease phase. An Esaote USscanner with a MyLab25 12 MHz linear probe was used for all USassays, which were performed by the same rheumatologist, with experience in musculoskeletal US. The US assessment searched for and quantified (grades 0-1-2-3) subclinical synovitis (coexistence of synovial hypertrophy and power Doppler signal) in the areas mentioned above.
Results 40 patients (70% women), mean age 51.1±11.9 years, mean disease duration 2.4±11.3 years, were included. The most-commonly involved joints during the attacks were: MCP (47.5%), wrist (27.5%), PIP (17.5%). In 47% of patients, the duration of the attackswas< 48hours. Rheumatoid factor (RF) and ACPA (CCP2 commercial test) were positive in 52.5% and 72.5% of patients, respectively. Seventy per cent of patients were treated with DMARDs, most frequently hydroxychloroquine. US showed a power Doppler signal in 13 patients (32.5%), most-frequently in the carpal joints (30%), and second MCP (25%), and 87.5% of patients had some degree of synovial hypertrophy, of which the highest degree was in the carpal joints (35%) and MCP (34.3%). No significant differences in US results were found between ACPA-positive or ACPA-negative patients (Table 1). US performed in 4 patients during RP attacks showed 3 had active synovitis (synovial hypertrophy and power Doppler signal).
Conclusions US showed most patients with pure PR have some degree of synovial hypertrophy in the joints of the hand in the asymptomatic phase, but only one third had subclinical synovitis (synovial hypertrophy and power doppler signal), with no differences between ACPA-positive and ACPA-negative patients.
Disclosure of Interest None Declared