Hand ultrasound patterns in rheumatoid and psoriatic arthritis: the role of ultrasound in the differential diagnosis

Many rheumatic diseases may present with an inflammatory joint syndrome, affecting the small joints of the hands, of which rheumatoid (RA) and psoriatic arthritis (PsA) being one of the most common. The aim of this systematic review was to focus on the literature evidence regarding the added value of ultrasound (US) of the hand in the differential diagnosis between RA and PsA. Pubmed and Scopus were searched to identify original manuscripts, published in the last 20 years utilising ultrasonography to reveal specific hand US patterns. Studies were eligible if they: (1) included adults (over 18 years) with a diagnosis of RA/PsA; (2) were published in the English language; (3) were published in peer-reviewed journals; (4) included description of the US machine; (5) used US for assessment of hand joints, periarticular tissues and nails. The search yielded 322 published studies, of which 16 were deemed relevant and were included in the present study. Overall, there was heterogeneity with regard to the pathology examined. Based on the included studies analysis, hand US patterns have several basic features to be considered—location of gray scale (GS) inflammatory findings, involvement of periarticular soft tissue, distribution and extent of Doppler signal (intra- and peri-articular), bone reaction, shape and location of erosions, involvement of tendons without synovial sheath, involvement of enthesis and nail abnormalities. Future research could focus on determining the sensitivity and specificity of the different US detected hand patterns in patients with early arthritis.