Giant cell arteritis associated with mononeuritis multiplex and complement-activating 19S IgM rheumatoid factor

Giant cell arteritis is a necrotizing granulomatous arteritis of large arteries, especially the aorta and its branches. Mononeuritis multiplex is a peripheral sensorimotor neuropathy usually producing foot or wrist drop, commonly associated with necrotizing arteritis of small and medium-sized arteries. Rheumatoid vasculitis is an example of the latter type of arteritis associated with high-titer 19S IgM rheumatoid factor typically occurring in patients with long-standing erosive rheumatoid arthritis. This report describes a 71-year-old man with biopsy-proved giant cell arteritis, mononeuritis (foot drop) multiplex, and high-titer complement-activating rheumatoid factor without rheumatoid arthritis. Possible pathogenic relationships are discussed.