This form of vasculitis is seen in immunologic disorders such as systemic lupus erythematosus (Chapter 5) that are associated with autoantibody production. The vascular lesions resemble those found in experimental immune http://ebooksmedicine.net *Thegranulomasofgiantcellarteritisarefoundwithinthevesselwallaspartoftheinflammationcomprisingthevasculitis,butneednotbepresenttorenderthediagnosis.Thegranulomasofgranulomatosiswithpolyangiitisarelarger,spanningbetweenvessels,andassociatedwithareasoftissuenecrosis.ANCA, Anti-neutrophilcytoplasmicantibodies.FromSeidmanMA,MitchellRN:Surgicalpathologyofsmall-andmedium-sizedvessels.InWinters,GL,ed.,Current concepts in cardiovascular pathology,Philadelphia,2012,Saunders.
AortaLarge vessel vasculitis Granulomatous disease (e.g., giant cell arteritis, Takayasu arteritis) SLE (e.g., SLE vasculitis) Paucity of immune complexes (often with ANCA) Vasculitis without asthma or granulomas (microscopic polyangiitis) Granulomas, no asthma (granulomatosis with polyangiitis) Eosinophilia, asthma, and granulomas (Churg-Strauss syndrome) Medium vessel vasculitis Immune complex mediated (e.g., polyarteritis nodosa) Anti-endothelial cell antibodies (e.g., Kawasaki disease) ArteriesVeinsArteriolesVenules
Fig. 10.22 Vascularsitesinvolvedinthemorecommonvasculitidesandtheirpresumptiveetiology.Notetheconsiderableoverlapindistributions.ANCA,anti-neutrophilcytoplasmicantibody;IgA,immunoglobulinA;SLE,systemiclupuserythematosus.(Data from Jennette JC, Falk RJ: Nosology of primary vasculitis, CurrOpinRheumatol19:17, 2007.)
IgA Cryoglobulin Other (e.g., (e.g., Henoch-(e.g., cryoglobulin Goodpasture Schönlein purpura) vasculitis) disease) http://ebooksmedicine.net complex–mediated disorders, such as the Arthus phenomenon and serum sickness, and in some cases contain readily identifiable antibody and complement. Often, however, this type of vasculitis is a diagnostic challenge. Only rarely is the specific antigen responsible for immune complex formation known, and in most instances it is not clear whether the pathogenic antigen-antibody complexes are deposited into the vessel wall from the circulation or form in situ. In fact, in many suspected cases, even the antigen-antibody deposits are scarce, perhaps because the immune complexes have been degraded by the time of biopsy.
Immune complex deposition is also implicated in the following vasculitides:
Drug hypersensitivity vasculitis. In some cases, drugs (e.g., penicillin) appear to act as haptens by binding to host proteins; other agents are themselves foreign proteins (e.g., streptokinase). In either case, antibodies directed against the drug-modified proteins or foreign molecules result in immune complex formation. The clinical manifestations can be mild and self-limiting, or severe and even fatal; skin lesions are most common. It is always important to consider drug hypersensitivity as a cause of vasculitis, since discontinuation of the offending agent usually leads to resolution.