Palindromic onset of rheumatoid arthritis. Clinical, synovial fluid, and biopsy studies.

Five patients had episodic arthritis consistent with palindromic rheumatism that evolved into definite or classic rheumatoid arthritis after 1 or more years. Synovial effusions during palindromic episodes had various leukocyte counts; mononuclear cells predominated in 4 patients. Neither these effusions nor needle synovial biopsies that showed subacute superficial inflammation and microvascular disease allowed any prediction that the disease would evolve into rheumatoid arthritis. Electron-dense deposits in vessel walls suggested circulating immune complexes. There was also prominent, unidentified debris in vessel walls and in phagocytic vacuoles, which might also be important in pathogenesis.