Zabotti A, Sakellariou G, Tinazzi I, et al. - This study was sought to distinguish the characteristic lesions in psoriatic arthritis (PsA) dactylitis of the hands, evaluate the reliability of musculoskeletal ultrasonography (Msk-US) in scoring those lesions and develop a Dactylitis global sonographic (DACTOS) score. Twelve rheumatologists participated in a three-round Delphi procedure and consensus meeting to agree on the sonographic elementary lesions defining dactylitis and on the composition of a global sonographic score after a systematic literature review on the use of Msk-US in PsA dactylitis. Researchers conducted a web-based and a patient-based intra-rater and inter-rater reliability exercise to evaluate those lesions included in the score. It was shown that the novel DACTOS score was a reliable measure to interpret the multiple characteristic sonographic features of dactylitis. The DACTOS score serves a beneficial global analysis of dactylitis of the hand and can represent a support to clinical diagnosis as well as a beneficial tool for the management and research in patients with PsA with dactylitis.