RESUMEN
Although both systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) may lead to joint deformity, SLE arthritis is typically non-erosive and often accompanied by Jaccoud's deformity. Therefore, we examined characteristics of joint and tendon lesions in patients with SLE and RA by ultrasonography. Fifteen treatment-naïve SLE patients and 40 treatment-naïve RA patients with joint symptoms were included in this study. The hand joints and related tendons were ultrasonographically examined using grey-scale (GS) and power Doppler (PD). Joint involvement was comparably observed in patients with SLE and RA (80% versus 95%, p = 0.119). However, tendon involvement was more frequent in SLE than in RA (93% versus 65%, p = 0.045), especially in the wrist joints (73% versus 40%, p = 0.037). When we investigated the intensity of US findings, the joint synovitis score (GS + PD) per affected joint was lower in SLE than RA (2.0 versus 2.6, p = 0.019), while tendon inflammation score was not significantly different (2.1 versus 2.2, p = 0.738). Finally, the examination of concordance between joint and tendon involvement in the same finger revealed that joint lesion appeared in only 49% of fingers having tendon involvement in the SLE group, which was significantly less than 74% in the RA group ( p = 0.010). Thus, as compared with RA, SLE arthropathy is characterized by the predominance of tenosynovitis/periextensor tendon inflammation, which is likely to develop independently from joint synovitis.