Peritenon extensor tendon inflammation in psoriatic arthritis is an enthesitis-related lesion

Objective. To analyze the association between enthesitis, synovitis, and peritenon extensor tendon inflammation (PTI) in psoriatic arthritis (PsA). Methods. PsA patients with swelling of metacarpophalangeal joints were included. Greyscale and power Doppler (PD) were used for synovitis and PTI ultrasound identification. Madrid Sonographic Enthesis Index (MASEI) was used for enthesitis assessment. PD activity was evaluated using PD item of MASEI and PD Outcome Measures in Rheumatology (OMERACT) definition. Results. Synovitis had no association with enthesitis. PTI was associated with PD MASEI and PD OMERACT. Only PD OMERACT showed a positive correlation with PTI. Conclusion. In PsA, PTI is associated to enthesitis, as opposed to synovitis.