Giant Cell Arteritis

Basics

Description

  • Chronic vasculitis of large- and medium-sized vessels that occurs among individuals over 50 yr of age with a predominance for females
  • Often referred to as temporal arteritis (TA)
  • Most common primary vasculitis in adulthood
  • Age is the greatest risk factor:
    • Rare in patients <50 yr old
    • >90% are >60 yr old with median age of onset 72 yr
    • Prevalence in individuals >50 yr is estimated at 1:500
  • Increased prevalence in Northern latitude with highest incidence in those of Scandinavian descent
  • 2–4 times more common in women
  • Rare in African American, Latino, and Asian patients
  • Most commonly causes inflammation of arteries originating from the arch of the aorta
  • Although usually clinically silent, involvement of the thoracic aorta occurs in a significant minority of patients, and aortic aneurysm or dissection may result
  • Thoracic aortic aneurysm is a late manifestation with an incidence 17 times those without giant cell arteritis (GCA)
  • Abdominal aortic aneurysm is about twice as common in those with GCA
  • Occlusive arteritis may involve thrombosis of the ophthalmic artery resulting in anterior ischemic optic neuropathy (AION) and acute visual loss:
    • Visual symptoms are an ophthalmic emergency
  • Inflammation of arteries supplying the muscles of mastication results in jaw claudication and tongue discomfort
  • Pathologic specimens feature patchy mononuclear granulomatous inflammation resulting in a markedly thickened intima and occlusion of the vessel lumen

Genetics

Genetic predisposition is linked to HLA-DRB*04 – 60% prevalence

Etiology

  • Unknown
  • Genetic, environmental, and autoimmune factors have been identified
  • Often coexist with polymyalgia rheumatica (PMR) (40–60% of GCA patients have PMR)
  • Recently identified association with varicella zoster virus virion, antigen, and DNA w/in vessel wall

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