Ultrasonographic Evidence of Predominance of Acute Extracapsular and Chronic Intrasynovial Patterns in 100 Cases of Psoriatic Hand Dactylitis

Objective. To use ultrasonography to study whether the duration of psoriatic dactylitis was associated with different patterns of extracapsular and synovial-based involvement. Methods. One hundred cases of hand dactylitis from 85 patients with psoriatic arthritis (PsA) were consecutively enrolled in a multicenter cross-sectional study and divided into 2 groups according to dactylitis duration (shorter or longer than the median: 20 weeks). All dactylitis fingers were investigated using high-frequency ultrasound both in greyscale (GS) and power Doppler (PD), evaluating the presence of flexor tenosynovitis, soft tissue edema, subcutaneous PD signal (PDS), extensor tendon involvement, and joint synovitis. Results. Cases with a shorter dactylitis duration (< 20 weeks) had a significantly higher prevalence of GS flexor tenosynovitis of grade > 2, PD flexor tenosynovitis, soft tissue edema, and subcutaneous PDS (p = 0.001, p < 0.001, p < 0.05, and p = 0.001, respectively). However, the presence of synovitis in GS and PD mode (in both cases at proximal interphalangeal level) was more frequent in patients with longer dactylitis duration (p < 0.001). When detected in the chronic form, flexor tenosynovitis was grade 2 or lower. Conclusion. In a large cohort of PsA hand dactylitis, we found a predominant extracapsular inflammation (flexor tenosynovitis and soft tissue edema) in early cases and a high prevalence of joint synovitis at proximal interphalangeal level in the chronic form. However, longitudinal imaging studies are needed to clarify these aspects.