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.