Ultrasonography in the diagnosis and management of psoriatic dactylitis.

OBJECTIVE: To determine the ultrasonographic features of dactylitis in psoriatic arthritis (PsA).

METHODS: Seventeen patients with PsA presenting with a total of 25 dactylitic fingers and toes underwent ultrasonographic examination of the digits with a 7.5 or 10 MHz transducer.

RESULTS: Flexor tenosynovitis was present in 96% (24/25) of dactylitic digits. Articular synovitis was present in 52% (13/25) of dactylitic digits. Subcutaneous soft tissue enlargement was present in all digits. The presence of articular synovitis in a dactylitic finger on ultrasonography correlated with the presence of joint space narrowing and periostitis on plain radiography.

CONCLUSION: Dactylitis in PsA is due to both flexor tenosynovitis and articular synovitis. Dactylitis in PsA has an increased incidence of articular synovitis, which was associated with the development of articular damage as assessed by plain radiography.