Giant Cell Arteritis



Giant Cell Arteritis


Surya V. Seshan, MD





Key Facts


Terminology



  • Granulomatous arteritis of aorta and its major branches


Etiology/Pathogenesis



  • Possible triggers include exposure to several upper respiratory disease pathogens


  • Associated with HLA-DRB1 and HLA-DR4 gene alleles


  • Cell-mediated immune mechanism


Clinical Issues



  • Usually > 50 years


  • Female predilection (M:F = 1:2-6)


  • Symptoms of polymyalgia rheumatica (50-75%)


  • Elevation of acute phase reactants in active disease (ESR, CRP)


  • Rapid response to steroid treatment


  • Microscopic hematuria, particularly with increased disease activity


Image Findings



  • MR angiography and high spatial configuration


  • Angiography of aorta and great vessels


Microscopic Pathology



  • Granulomatous inflammation extending from media to intima and adventitia with disruption of elastic lamina by giant cells


Top Differential Diagnoses



  • Takayasu arteritis


  • Rheumatoid aortitis


  • Atherosclerotic arterial disease


  • Other systemic vasculitides


  • Fibromuscular dysplasia







Cross section of a temporal artery shows adventitial, medial, and intimal active arteritis image with occlusive changes. Numerous multinucleated giant cells are noted within the wall.






MR angiogram shows an irregular, long-segment stenosis of the left common carotid artery image and brachiocephalic artery stenosis image due to mural thickening. These findings are typical of GCA.


TERMINOLOGY


Abbreviations



  • Giant cell arteritis (GCA)


Synonyms



  • Temporal arteritis


  • Cranial arteritis


  • Horton syndrome


Definitions



  • Chapel Hill Consensus Conference



    • Granulomatous arteritis of aorta and its major branches, with predilection for extracranial branches of carotid artery


    • Often involves temporal artery


    • Usually occurs in patients > 50 years of age and is often associated with polymyalgia rheumatica


  • American College of Rheumatology Criteria



    • Age ≥ 50 years


    • New onset of localized headache


    • Temporal artery tenderness or decreased temporal artery pulse


    • Elevated ESR ≥ 50 mm/hr


    • Biopsy of artery with necrotizing arteritis with mononuclear infiltrates or granulomatous process


    • Presence of any 3 or more of above yields high sensitivity and specificity


ETIOLOGY/PATHOGENESIS


Environmental Exposure



  • Etiology unknown


  • Possible triggers include exposure to several upper respiratory disease pathogens



    • Mycoplasma/Chlamydia pneumoniae


    • Parvovirus B19, human parainfluenza virus type I


    • Herpes simplex virus


Genetic



  • Associated with HLA-DRB1 and HLA-DR4 gene alleles


  • ICAM-1 gene polymorphism (R241)


Pathogenesis



  • Autoimmune cell-mediated mechanism



    • T-cell mediated process



      • CD4(+) T-helper cells in inflammatory site


      • T-cell activation locally in arterial wall following activation of antigen presenting cells (e.g., dendritic cells in adventitia)


    • Activation of monocytes/macrophages responsible for systemic symptom


    • Destructive vascular inflammation may lead to vaso-occlusive intimal proliferation or aneurysm formation depending on type of arterial vessel involved


    • Interferon gamma produced from T cells is crucial in giant cell reaction in GCA


  • Role for humoral-mediated immunity is suggested



    • Elevated serum immunoglobulins


    • Detection of circulating immune complexes


    • Rare immune complex deposition


CLINICAL ISSUES


Epidemiology

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Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Giant Cell Arteritis

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