Episodic arthropathy in adult cystic fibrosis.

Five (8.5 per cent) of 59 adult patients with cystic fibrosis described a characteristic arthropathy which was episodic, self-limiting and polyarticular, affecting large and small peripheral joints without evidence of progression to joint damage. The five patients with arthropathy did not differ from the remaining 54 with respect to manifestations of cystic fibrosis. Synovial fluid obtained from two patients during acute episodes was clear, viscous and contained no cells. Biopsies of synovial membrane from the same patients demonstrated prominent congested blood vessels with some synovial oedema, but no evidence of inflammation. Immunofluorescent staining of synovial membrane demonstrated characteristic intimal deposition of immunoglobulin in the vessels. In one of the two patients acute arthropathy was accompanied by transient cutaneous vasculitis, circulating immune complexes and lowered serum complement levels, which suggests that the episodic arthropathy in at least some patients with cystic fibrosis is mediated by an immune mechanism.