Giant Cell Arteritis (Gca)

Basics

Chronic vasculitis of large- and medium-sized vessels that occurs among individuals over 50 yr of age
Often referred to as temporal arteritis (TA)
Median age of onset is 72 yr
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 TA
Abdominal aortic aneurysm is about twice as common in those with giant cell arteritis (GCA)
Pathologic specimens feature patchy mononuclear granulomatous inflammation resulting in a markedly thickened intima and occlusion of the vessel lumen
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
Age is the greatest risk factor:
- Rare in patients <50 yr old
- >90% are >60 yr old
- 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
There is a strong association with polymyalgia rheumatica (PMR) ∼50%

Genetics
Genetic predisposition is linked to HLA-DR4 – 60% prevalence

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