Background/Purpose: In the treatment of rheumatoid arthritis (RA), the early diagnosis and early medical treatment via tight control have become increasingly important with the advent of biological therapy. Ultrasonography (US) for the affected joints enables the evaluation of synovial hypertrophy, effusion and bone erosion in real time. US is a reliable method that can detect more erosive sites than radiography. US is now utilized widely and is a reliable tool among rheumatologists for diagnosing RA and evaluating the disease activity. However, many patients have swollen, deformed and painful joints due to overuse and advancing bone destruction. This study was conducted to clarify the relationship between the systemic disease activity, local disease activity using US and a synovial histopathological evaluation in RA patients in remission (Disease Activity Score [DAS] 28-ESR[4]<2.6).

Methods: Between March 2011 and April 2017, 176 joints were surgically treated among all RA patients in remission, and synovial biopsies were performed at the time of surgery. Among them, a total of 52 fingers, 32 wrists, 57 toes, 3 ankles, 12 elbows, 3 shoulders and 17 knees were investigated. Just before surgery, the US probe was placed on the joints to evaluate the activity of local synovitis. The maximum grade of power Doppler (PD) signal was determined, ranging from 0 to 3. The serum C reactive protein (CRP), matrix metalloproteinase-3 (MMP-3) and DAS28 values were also examined just before surgery. A histopathological examination of the gathered synovium at the surgical site was performed using the Rooney score (RS). Biological disease-modifying antirheumatic drugs (BIO) were used in 73 cases, namely infliximab in 8 cases, etanercept in 10, adalimumab in 10, tocilizumab in 28, abatacept in 5, certolizumab pegol in 2 and golimumab in 10.

Results: The PD score was grade 0 in 76 cases, 1 in 61 cases, 2 in 30 cases and 3 in 9 cases. The average CRP was 0.17 mg/dL, and MMP-3 was 94.6 ng/mL, both low values. The three items of lymphocytes in the RS score showed low values, while synoviocyte hyperplasia and fibrosis showed high values due to a secondary reaction after inflammation at the joints. Group L consisted of 76 joints of grade 0, Group H included 61 joints of grade 1, 30 joints of grade 2 and 9 joints of grade 3. The values of MMP-3, synovium hyperplasia, lymphocyte infiltration and blood vessel hyperplasia were markedly low in Group L. Small Joints (SJ) consisted of 144 joints with fingers, wrists, feet and ankles. Large Joints (LJ) consisted of 32 joints with elbows, shoulders and knees. The values of MMP-3, synovium hyperplasia and high value were markedly low in SJ cases with blood vessel hyperplasia. Patients using BIO showed low values for CRP, synovium hyperplasia and lymphocyte infiltration.

Conclusion: The systemic disease activities, as indicated by DAS28, CRP and MMP-3, of RA patients in remission were low. However, synovitis was clearly present based on ultrasonography and histological findings of the surgical joints of PD-positive RA patients in remission.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/ultrasonography-and-synovial-histology-in-the-ra-patients-in-remission/