Lower limb enthesopathy in patients with psoriasis without clinical signs of arthropathy: a hospital-based case - control study

Background: Psoriasis is associated with a form of spondyloarthropathy in 10-30% of cases. A major feature of psoriatic arthritis is enthesitis. In some patients with psoriasis the presence of enthesitis could be under-diagnosed. Objective: To investigate the presence of lower limbs entheseal abnormalities in patients with chronic plaque psoriasis without signs and symptoms of psoriatic arthritis. Methods: Thirty patients with psoriasis and 30 controls underwent ultrasonographic evaluation of Achilles, quadriceps, patellar entheses and plantar aponeurosis. Ultrasonographic findings were scored according to the Glasgow Ultrasound Enthesitis Scoring System (GUESS). Results: Mean GUESS score was significantly higher in patients with psoriasis as compared with controls: 7.9 (0.6) vs 2.9 (0.3); p<0.0001. In particular, the thickness of all tendons examined was significant higher in cases than in controls (p<0.0001), as well as the number of enthesophytes in all sites examined. In both cases and controls, the GUESS score was directly correlated with age (r = 0.22; p = 0.008), body mass index (r = 0.23, p = 0.0067) and waist circumference (r = 0.17; p = 0.02). In contrast, the GUESS score was not correlated with the duration and severity of psoriasis according to the Psoriasis Area and Severity Index (r = 0.03; p = 0.8) and body surface area involvement (r = 0.07; p = 0.6). Conclusions: Entheseal abnormalities can be documented by ultrasonography in clinically asymptomatic patients with psoriasis. These findings could be related to a subclinical entheseal psoriatic inflammation. We suggest close follow-up of patients with psoriasis with entheseal abnormalities for early diagnosis of psoriatic arthritis.