Synovitis with non-specific histological changes in synovium in chronic sarcoidosis.

Polyarthritic episodes in seven patients during the course of chronic sarcoidosis involved the knees and less frequently other joints. Synovial effusions were non-inflammatory or mildly inflammatory. Needle synovial biopsies 10 days to seven weeks after the onset of joint symptoms have revealed varying patterns, including mild lining cell proliferation, occasional vascular congestion, diffuse infiltrates with lymphocytes and histiocytes, but no granulomas. These studies show distinctly less inflammation than in rheumatoid arthritis. Granulomas need not be identifiable in synovium in all chronic sarcoidosis with arthritis.