Background Many studies revealed subclinical enthesitis in psoriasis patients without any rheumatic complain. Most of these studies utilize diagnostic high frequency ultrasound (US) in detection of abnormal changes at the enthesis^1,2. They mostly include the entheses of the lower limb and included only patients with the plaque type psoriasis, moreover, no attempts made to report similar changes in psoriatic arthritis (PsA).

Objectives Our primary outcome was to study the ultrasonographic pattern of subclinical enthesitis in psoriasis patients, including those who also developed PsA. Also we aim to elaborate if there was an associated link between enthesitis severity on one hand and psoriasis severity, duration, type and distribution. Selected stites were 5 entheses in the lower limb and 3 in the upper limb: Quadriceps tendon insertion, Inferior pole of the patella, Tibial tuberosity, Achilles tendon, Plantar fascia, Triceps tendon insertion, Common Extensor origin, Common Flexor origin.

Methods We conducted an observational cohort study on 100 psoriasis patients. Exclusion criteria included those who had any inflammatory Rheumatic Complaint before the onset of Psoriasis, or if they had any Degenerative, Metabolic and Endocrinal causes of Enthesopathy. History, clinical examination, calculation of Psoriasis severity using PASI & BSA and US examination were obtained for all patients.

Results There were 60% female. mean age 36.52 and range from 16-45 years old. Plaque psoriasis 60%,pustular and palmo-plantar 12% each. Erythrodermic psoriasis 8% and Guttate 4%. Four patients had Nail only psoriasis. PsA according to CASPAR criteria was present in 56% of our patients. US detected 588 subclinical sites out of 1600 (36.75%). Psoriasis had more subclinical enthesopathy than PsA patients 51.7% vs. 48.3% (p=0.000). The subclinical enthesopathy detected by US were more common in the asymmetric oligoarthritis subtype 28 site out of 64 (43.75%), and the predominant SpA subtype 132 site out of 320 (41.25%) considered as “SpA like”, than Symmetric Polyarthritis 72 out of 256 (28.1%) and predominant DIP 52 out of 256 (20.3%) “RA like”. Guttate had more subclinical sites 32 out of 64 (50%) than Plaque subtype 424 out of 960 (44.2%).

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Conclusions US revealed subclinical enthesopathy in all subtypes of skin psoriasis and PsA patients both in lower and upper limb (systemic polyenthesopathy).US revealed different predilections of tissue involvements in subclinical enthesopathy between Psoriasis and PsA patients. More chronic changes were seen in psoriasis (seen as erosions and Entheseophytes), while more active changes were seen in PsA (tendon thickness and bursitis). Pointing to a different immune mechanisms and targets in psoriasis responsible for predominant changes at bone side that shifts with onset of PsA to predominate in the tendon side.Psoriasis features as duration, PASI and BSA involvement found to be significantly moderately correlated with presence/number of subclinical enthesopathy in PsA but not in psoriasis

References

1. Gisondi, P; Tinazzi, I; El-Dalati, G; et al. (2008): Lower limb enthesopathy in patients with psoriasis without clinical signs of arthropathy: a hospitalbased case–control study. Ann Rheum Dis, 67: 26-30.

2. Mandl, P.; Niedermayer, D.S.; Balint, P.V. (2012): Ultrasound for enthesitis: handle with care! Ann Rheum Dis, 71: 477-479.

Disclosure of Interest None declared

DOI 10.1136/annrheumdis-2014-eular.4273