Ultrasound in Evaluation of Subclinical Enthesitis of Extensor Digitorum Tendon and Nail Unit Changes in Psoriasis

Abstract

Psoriatic arthritis (PsA) is a chronic multifaceted inflammatory musculoskeletal disease, associated with psoriasis. The prevalence of PsO in the general population ranges between 0.1 and 2.8% and between 6 and 42% of patients with PsO can develop arthritis. Nail changes appear to result from the close relationship between the nail and the enthesis of the distal interphalangeal joint (DIP) at extensor digitorum tendon insertion. Subclinical inflammation at entheseal level detected by US has been shown in patients with PsO without previous history of arthropathy or PsA. Objective: To detect subclinical arthritis or enthesitis at DIP fingers and nail unit changes in psoriatic patient for early detection of psoriatic arthritis. Patients and Methods: This study included thirty adult patients with clinical evidence of Psoriasis were collected from outpatient clinic of Dermatology departments of Ain Shams University Hospitals and thirty healthy controls from our department of physical medicine, Rheumatology and Rehabilitation. The study was conducted from February 2019 to January 2020. Written informed consent was taken from all patients and approval from ethical committee. Results: We found distal interphalageal joint affection in form of synovial hypertrophy and effusion with PD was found in 4 cases (13.3%). We found Enthesophyte with power Doppler (PD) was found in 17 out of 30 (56.7%) range from 1-8 a mean ± SD 2.35 ± 1.73 of cases. We found nail irregularities by ultrasound in all cases (30 patients, 100%), it ranged from 2-10 with a mean ± SD 5.47 ± 2.4 on comparison between cases and control in NAPSI score by clinical examination versus Nail irregularities ultrasonographic examination the sensitivity of Ultrasound was (100%) mean all cases (20 case) showed clinically positive by NAPSI were positively affected by ultrasound And specificity (30%) due to there were (7cases) were negative by NAPSI and were positive by ultrasound and (3cases) negative by NAPSI and Ultrasound. Conclusion: Power Doppler ultrasound is an important tool for examining entheses in patients with psoriasis, and the presence of a high PASI score, an in¬crease long disease duration could be considered as predictive parameters for the presence of psoriatic en-thesitis, There was a significant increased prevalence of US extensor tendon enthesopathy in fingers with involved nails, This feature might support the nail entheseal pathogenesis theory at DIP level.