Extrascapular inflammation was common in patients with psoriatic arthritis (PsA), particularly among early cases, according to research results published in the Journal of Rheumatology.

In a multicenter cross-sectional study, researchers assessed 100 cases of hand dactylitis from 85 consecutive patients with PsA. They divided patients into 2 groups according to the duration of dactylitis, either shorter or longer than the 20-week median. The researchers used high-frequency gray scale and Power Doppler ultrasound to assess fingers with dactylitis for the presence of flexor tenosynovitis, soft tissue edema, subcutaneous Power Doppler signal, extensor tendon involvement, and joint synovitis.

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Psoriatic arthritis duration, tender joint count, swollen joint count, erythrocyte sedimentation rate, and C-reactive protein were similar in both groups, but mean values of the Leeds Dactylitis Index score and the patient pain visual analog scale were significantly higher in the shorter duration group (P <.001).

Investigators found ≥1 ultrasound abnormality in all patients. They found flexor tenosynovitis in 88% of dactylitis, 46% with grade ≥2. Patients in the shorter duration group had a significantly higher presence of gray scale (P =.001) and Power Doppler flexor tenosynovitis (P <.001), soft tissue edema (P <.05), and subcutaneous Power Doppler signal (P =.001). Conversely, synovitis identified via both gray scale and Power Doppler ultrasound was more common in patients in the longer-duration group (P <.001).

Researchers noted flexor tenosynovitis plus soft tissue edema in 79% of patients and observed flexor tenosynovitis plus joint synovitis of ≥1 joint in 31%.

Researchers noted no differences in the presence of ultrasound abnormalities — specifically flexor tenosynovitis, soft tissue edema, and joint synovitis — when they compared patients treated vs not treated with conventional synthetic disease-modifying antirheumatic drugs, regardless of subgroup.

Study limitations included the cross-sectional nature of the study; symptom duration was only obtained via medical history. Another limitation was the artificial definition of acute or chronic dactylitis applied according to the median symptom duration. Finally, the researchers noted that enrolled patients were undergoing differing drug therapies.

“This is the first multicenter study that evaluated the relationship between [ultrasound] lesions and dactylitis duration in a large PsA hand dactylitis cohort,” the researchers concluded. “Our findings could suggest a possible change from a predominant extrascapular pattern in the early phase to an intrasynovial pattern in the chronic evolution. However, longitudinal imaging studies are need[ed] for clarifying these aspects.”

Reference

Girolimetto N, Macchioni P, Tinazzi I, et al. Ultrasonographic evidence of predominance of acute extracapsular and chronic intrasynovial patterns in 100 psoriatic hand dactylitis [published online May 15, 2019]. J Rheumatol. doi:10.3899/jrheum.190046