Giant-cell vasculitides.

Although many of the vasculitides within the classification of the American College of Rheumatology can have a component of granulomatous inflammation with giant cells, two (ie, giant-cell [temporal] arteritis and Takayasu arteritis) are characterized by infiltrates that are dominated by granulomatous and/or giant-cell-containing inflammation. Furthermore, granulomatous and/or giant-cell dominant infiltrates can characterize disseminated giant-cell arteritis, granulomatous vasculitis of the central nervous system, localized giant-cell arteritis, mesenteric inflammatory veno-occlusive disease, primary cutaneous phlebitis, and giant-cell phlebitis of mesenteric veins and/or omentum. Like the other systemic vasculitides, there is considerable clinicopathologic overlap between these giant-cell vasculitides. Indeed, they are likely closely related, but how they specifically relate to each other is not clear. Their accurate diagnosis is important; because serious morbidity and even death may occur, if proper treatment is delayed or if excessive immunotherapy is given.