The histopathological synovitis score evaluates in a graded approach, as is largely usual for diagnostic histopathological scores, the immunological and inflammatory changes caused by synovitis. A synovitis score of between 1 and ≤ 4 is classified as low-grade (osteoarthritis-related synovitis, post-traumatic synovitis, meniscopathy-related synovitis and synovitis in hemochromatosis). Synovitis scores of between ≥ 5 and 9 are classified as high-grade synovitis (rheumatoid arthritis, psoriatic arthritis, Lyme's arthritis, post-infection/reactive arthritis and peripheral arthritis in Bechterew disease); sensitivity is 61.7% and sensitivity 96.1%. According to receiver operating characteristic (ROC) analysis (AUC: 0.8-0.9), diagnostic value is good. National and international acceptance of the synovitis score has grown since the first publication in 2002 and a related follow-up publication in 2006. PubMed data analysis (as of 11.01.2017) yielded the following citation values according to "cited by PubMed Central articles" for two publications relating to the synovitis score: there were 29 cited-by-PubMed articles for DOI: 10.1078/0344-0338-5710261 , and 44 cited-in-PubMed articles for the second publication, DOI: 10.1111/j.1365-2559.2006.02508 . This makes a total of 73 PubMed citations over a period of 15 years, thereby evidencing the score's international acceptance. Immunohistochemical determination of a number of CD antigens relevant to inflammation has been proposed to further specify the synovitis score for the purposes of risk stratification of high-grade synovitis (e.g., risk of progression and sensitivity to biological agents).
Keywords: Immunohistochemistry; Osteoarthritis; Rheumatoid arthritis; Synovial tissue; Synovitis.