Morphometric analysis of blood vessels in synovial membranes obtained from clinically affected and unaffected knee joints of patients with rheumatoid arthritis.

Synovial tissues from inflamed and noninflamed knee joints of 13 patients with untreated rheumatoid arthritis were examined for vascular proliferation and morphological alteration of endothelial cells. Perivascular mononuclear cell infiltration and increased thickness of the synovial lining layer were noted in tissues from inflamed and noninflamed joints of patients with rheumatoid arthritis; vascular proliferation and morphological alteration of endothelial cells to resemble high endothelial venules were seen only in tissues from inflamed joints of patients with rheumatoid arthritis. These observations suggest that the migration of mononuclear cells from the peripheral blood to the perivascular areas and lining layer occurs before vascular proliferation and morphological alteration of endothelial cells.