Value of Hands Ultrasonography in the Differential Diagnosis Between Psoriatic Arthritis and Rheumatoid Arthritis

Abstract

ObjectivesPsoriatic arthritis (PsA) can mimic rheumatoid arthritis (RA) at an early stage, especially when psoriasis is lacking. In the absence of specific radiological and immunological markers, the differential diagnosis between these two diseases can be challenging. We aimed to determine whether hands ultrasonography (US) may be useful in the differential diagnosis between PsA and RA.MethodsWe conducted a cross‐sectional study including patients with PsA and RA. All wrists and small joints of the hands were examined using gray‐scale and Power Doppler US. The evaluated US lesions were: synovitis, tenosynovitis of extensor carpi ulnaris, extensor communis and flexor tendons, enthesitis of extensor tendons at distal interphalangeal joints, peritendon inflammation of extensor tendons, and soft tissue edema.ResultsSix hundred joints in 20 PsA patients and 900 joints in 30 RA patients were assessed. Extensor enthesitis was significantly more observed in PsA compared with RA (39.4 vs 26.3%, P = .006) with a significant higher frequency of enthesophytes and calcifications (P = .022 and P = .002, respectively). Peritendon inflammation of extensor digitorum tendons was observed in 13% of metacarpophalangeal joints in PsA patients versus 3% in RA patients with a significant difference (P < .001). Soft tissue edema was exclusively observed in PsA (1.5 vs 0%, P = .033). Power Doppler synovitis was significantly more frequent in RA (9.2 vs 5%, P = .002). Extensor carpi ulnaris tenosynovitis was significantly more frequent in RA (18.3 vs 2.5%, P = .017).ConclusionExtrasynovial US findings may be helpful to distinguish PsA from RA especially in patients with immunonegative polyarthritis and no evidence of psoriasis.

Ultrasonographic Insights into Peripheral Psoriatic Arthritis: Updates in Diagnosis and Monitoring

“…In US, enthesopathy and peritendon inflammation (including tenosynovitis and paratendinitis) are more frequent in PsA joints with synovitis than in RA, as described by most studies [ 15 , 16 ]. Abdelghani KB et al [ 17 ], however, could not demonstrate statistical differences between findings of peritendon inflammation in RA and PsA patients.…”

“…Regarding the amount of committed joints, PD positive synovitis in US is more frequent in RA, to the detriment of PsA [ 17 , 19 ], with no statistical difference for GS synovitis alone. In terms of joints affected, synovitis in RA often is present in multiple joints symmetrically, with metacarpophalangeal involvement being more frequent than in PsA.…”

“…In terms of joints affected, synovitis in RA often is present in multiple joints symmetrically, with metacarpophalangeal involvement being more frequent than in PsA. In PsA, conversely, it predominantly involves the proximal and distal interphalangeal (PIP and DIP) joints [ 17 , 18 , 20 ].…”

“…With the increasingly advanced technology of ultrasound machines, capable of producing high-resolution images with high-frequency transducers, greater attention has been directed towards the “mini entheses” of the hands. Those include the insertion of the extensor apparatus of the fingers at the middle and distal phalanges, the insertion of the flexor apparatus of the fingers on the volar surface of the distal phalanges, and the insertions of the collateral ligaments of the fingers [ 16 , 17 ]. Inflammatory involvement of these insertions supports the diagnosis of PsA and enhances our understanding of anatomical contiguity processes.…”

“…Firstly, ultrasound aids in distinguishing PsA from other inflammatory arthropathies through distinctive ultrasonographic patterns. Notably, studies have highlighted the higher specificity of extra-articular manifestations such as enthesitis, soft tissue edema, peritendinitis, dactylitis, and nail changes in PsA, contrasting with the predominantly articular findings observed in conditions like rheumatoid arthritis (RA) [ 17 , 18 , 56 ].…”