FRI0329 ASSOCIATION BETWEEN PERITENON EXTENSOR TENDON INFLAMMATION AND ENTHESITIS IN TUNISIAN PATIENTS WITH PSORIATIC ARTHRITIS

Background: Ultrasonography (US) is a useful tool in assessing psoriatic arthritis (PsA) by detecting synovitis and Power Doppler (PD) activity. Enthesitis is well known as a cornerstone of PsA physiopathology. Recently, more specific US features of PsA have emerged, such as peritenon extensor tendon inflammation (PTI) and edema of soft tissues, with value in the positive diagnosis of the disease. Objectives: The aim of our study was to determine the association between PTI, edema and enthesitis in PsA patients. Methods: Patients with peripheral PsA responding to the Classification Criteria for Psoriatic Arthritis (CASPAR) were included. US examination was performed by an experimented rheumatologist blinded to clinical data using a machine type Esaote MyLAb 60 with a linear probe of 6-18 MHz. Wrists, metacarpo-phalangeal (MCP), proximal inter-phalangeal (PIP) and distal inter-phalangeal (DIP) joints were assessed in mode B and PD. PTI was defined as a hypoechoic image surrounding the digitorum tendon with or without PD signal in the dorsal aspect of MCP joints. Soft tissue edema was defined as a diffuse enlargement of soft tissue around the flexor tendon, with an increased PD signal, from finger pad to MCP joint and was evaluated by volar scan. Enthesitis of the digitorum extensor tendon at the dorsal aspect of DIP joint and synovitis were defined according to the OMERACT definitions. A p Results: A total of 600 joints were assessed in 20 PsA patients, 8 men and 12 women, with a mean age of 55 ± 11 [33-77] years old. The mean disease duration was of 10±8 [1-34] years. Clinically, 25% of joints were tender and 6% were swollen. The mean DAPSA (Disease Activity in PSoriatic Arthritis) score was of 32±27 [4-112]. On US examination, synovitis was detected in 54 joints (9%), with PD signal in 53% of them. The sites of synovitis by decreasing order of frequency were: MCP in 38%, wrists in 26%, PIP in 19% and PID in 13% of cases. PTI was noted in 24 MCP joints (12%) with PD signal in one case, and soft tissue edema in 6 MCP joints (3%). Enthesitis was noted in 59 DIP joints (37%). The elementary lesions recorded were: enthesophytes in 64 %, erosions in 20 %, calcifications in 13 % and thickened and/or hypoechoic tendon in 12 % of cases. However, no PD signal at the enthesis was found. PTI and soft tissue edema had no association with enthesitis (p=0.399 and p=0.374 respectively). PD synovitis showed a significant association with enthesitis (p=0.034), but not with PTI and soft tissue edema. GS synovitis had no association with any of these lesions. Conclusion: Our study found PTI and soft tissue edema not to be associated with enthesitis as opposed to PD synovitis. A larger sample size is necessary to support the role of PTI as an enthesis related lesion in PsA patients. Disclosure of Interests: None declared