Quantitative histopathologic discrimination of rheumatic disorders using nuclear measurements of synoviocytes

To use several nuclear quantitative estimators of synoviocytes and advanced statistical tests to discriminate between rheumatic disorders with the purpose of providing an objective histopathologic differentiation and to illustrate the difficulty of establishing the implications of the vague diagnosis of chronic nonspecific synovitis.

Synovial histologic material from 48 patients, including a control group and those diagnosed with osteoarthritis, rheumatoid arthritis and chronic nonspecific synovitis, was analyzed. Both morphometric and stereologic nuclear measurements were assessed in each case, and several stepwise discriminant analyses were performed to obtain linear discriminant functions.

Differences in the nuclear size parameters were found between rheumatoid arthritis and the normal and osteoarthritis groups and between normal and chronic nonspecific synovitis. The volume-weighted mean nuclear volume was the most significant parameter. No differences were demonstrated between osteoarthritis and normal and chronic nonspecific synovitis or between rheumatoid arthritis and chronic nonspecific synovitis except for nuclear volume. Using stepwise discriminant analysis, 94% of the cases were correctly classified when differentiating the normal, osteoarthritis and rheumatoid arthritis groups. The overall accuracy of diagnosis decreased to 83% when chronic nonspecific synovitis samples were included. The misclassified samples were related mainly to normal cases and to osteoarthritis and chronic nonspecific synovitis cases.

This study emphasized that nuclear quantitative features of synoviocytes may be useful in differentiating rheumatic disorders objectively, especially in combination with discriminant analysis. Thus, nuclear changes in the synovium in chronic nonspecific synovitis show a closer similarity to normal and osteoarthritis than to rheumatoid arthritis.