Stereological analysis of the synovial membrane in rheumatic disorders: diagnostic value of volume-weighted mean nuclear volume estimation.

Quantitative evaluation of nuclear size of synoviocytes was performed on 48 synovial biopsies in various rheumatic disorders: osteoarthritis (n = 10), rheumatoid arthritis (11), and chronic non-specific synovitis (14). Thirteen tissue specimens from non-inflammatory synovial membrane were included as a control group. Using the point-sampled intercepts method, unbiased stereological estimates of volume-weighted mean nuclear volume (nuclear upsilon v) were obtained. A slight increase in nuclear volume was observed in osteoarthritis in comparison with the control group with an overlap in 90% of cases. However, in rheumatoid arthritis there was a significant increase of nuclear upsilon v. Significant differences were found between rheumatoid arthritis and the control and osteoarthritis groups (P < or = 0.001). In biopsies from patients diagnosed as chronic non-specific synovitis the averaged nuclear upsilon v values were between those in osteoarthritis and rheumatoid arthritis with a wide range of data. Similar, but less significant differences were demonstrated between rheumatic disorders when using mean nuclear area. Further analysis of chronic non-specific synovitis patients in combination with nuclear upsilon v estimates as a simple, unbiased, complementary tool are required to better establish the diagnostic value of nuclear stereology in the diagnosis of rheumatic disorders.