The role of pathology in the diagnosis of systemic vasculitis.

Pathologic processes are underlying defining features of systemic vasculitis. When these pathologic processes can not be observed directly, surrogate signs and symptoms of disease must be used to conclude that vasculitis is present in a patient and, if so, to determine what specific type of vasculitis is present. This review briefly describes the most defining pathologic features of giant cell arteritis, Takayasu arteritis, polyarteritis nodosa, Henoch-Schönlein purpura, cryoglobulinemic vasculitis, Kawasaki disease, microscopic polyangiitis, Wegener's granulomatosis and Churg-Strauss syndrome; and discusses how these pathologic features can be integrated with clinical and laboratory data to reach an actionable diagnosis.