Background Patients with cutaneous psoriasis (PSO) are at risk of developing psoriatic arthritis (PsA) overtime. The transition from skin disease to joint involvement is only partially characterized. Advanced imaging can depict signs of subclinical joint involvement.
Objectives To assess the prevalence of inflammatory MRI signs in a group of PSO patients with no history or presence of PsA, who showed bony changes (either erosions or osteophytes) on high-resolution peripheral quantitative computed tomography (HR-pQCT). Secondly, to examine whether inflammation on MRI is linked to the changes on HR-pQCT.
Methods PSO patients (with no arthritis, enthesitis nor dactylitis) underwent HR-pQCT and 1.5T magnetic resonance imaging (MRI) of the dominant hand. HR-pQCT scanning was conducted on the metacarpophalangeal (MCP) joints 2 and 3. Images were analyzed for the presence of periarticular changes as erosions and osteophytes. MRI images were acquired for the whole hand. Subsequent analysis of the images focused on the detection of osteitis, synovitis, tenosynovitis of the flexor tendon, periarticular inflammation at the MCP, PIP and DIP region of the 2nd to 5th finger, according to the definitions of key pathologies provided for the PsAMRIS scoring system.1 HR-pQCT and MRI images have been analyzed by 2 independent readers, mean time interval between both imaging techniques was 42 days. The study was conducted upon approval by the local ethic committee and the National Radiation Safety Agency (BfS). Patients participated after signing informed consent.
Results Images were acquired from 55 PSO patients (36.4% female) of mean age 49.5±11.5 years, mean disease duration 15.2±15.4 years and mean PASI score of 6.2±8.0. The most prevalent subtype was psoriasis vulgaris (73%), while nail psoriasis was present in 51% and scalp involvement in 29%. By HR-pQCT, 29% of the patients showed erosions, while all presented osteophytes. Of the 55 patients, 26 (47%) showed at least one of the mentioned inflammatory signs on MRI. In detail, osteitis was found in 6 out of the 55 patients (11%), while synovitis in 21 (38%); tenosynovitis and periarticular inflammation were detected each in 2 patients (4%). In the total sample, partial correlations (controlling for the influence of age and disease duration) between bony changes in HR-pQCT and osteitis as well as synovitis in MRI did not show any significant relations.
Conclusions Subclinical inflammatory lesions are prevalent in the joints of patients with PSO and affect about half of the patients. These findings suggest that a substantial proportion of PSO patients are affected by joint inflammation but are not classified as PsA. Interestingly, the relation of inflammatory-MRI changes to structural-CT changes in the joints of PSO patients is rather poor at the cross-sectional level, which will necessitate longitudinal assessment of joint inflammation in PSO patients.
Ostergaard M et al, J Rheumatol. 2009 Aug; 36(8): 1816-24
Disclosure of Interest None declared