Giant Cell Arteritis (Temporal Arteritis)

Giant cell arteritis is the most common primary large-vessel vasculitis of older adults, a granulomatous inflammation that characteristically involves the cranial branches of the aorta — including the temporal arteries — and can also affect the aorta itself. Its feared complication is sudden, often irreversible, visual loss from ischaemic involvement of the ophthalmic circulation.

Definition

Giant cell arteritis is a granulomatous arteritis of large and medium-sized arteries, with a predilection for the extracranial branches of the carotid artery and the aorta, occurring almost exclusively in people over the age of about 50.

Scope

This topic describes giant cell arteritis as a clinical entity within the large-vessel vasculitides: its typical vascular distribution, characteristic features, relationship to polymyalgia rheumatica, and the classification framework used to define it. It is reference and educational material and does not provide diagnostic or treatment instructions.

Key concepts

• Large-vessel and cranial-branch involvement
• Granulomatous arterial inflammation with giant cells
• Association with polymyalgia rheumatica
• Risk of anterior ischaemic optic neuropathy and vision loss
• Temporal artery biopsy and vascular imaging
• Marked elevation of acute-phase reactants
• Age over 50 as a defining feature

Mechanisms

Giant cell arteritis is understood as a T-cell-driven, granulomatous inflammation of the arterial wall in which dendritic cells, CD4+ T cells, and macrophages form infiltrates that may include multinucleated giant cells, often centred on the disrupted internal elastic lamina. The resulting intimal hyperplasia narrows the lumen and produces the ischaemic manifestations — headache, jaw claudication, and visual loss — while a strong systemic acute-phase response accounts for the constitutional symptoms and laboratory abnormalities.

Clinical relevance

Giant cell arteritis is the prototypical large-vessel vasculitis and a classic cause of new headache, jaw claudication, and visual symptoms in older adults; understanding its vascular pattern explains why it threatens vision and can involve the aorta. This entry describes the disease for reference and education and is not a guide to diagnosis or therapy for any individual.

Epidemiology

Giant cell arteritis occurs almost only in people older than 50 and rises in incidence with age, affects women more often than men, and is most frequent in populations of northern European descent, reaching its highest reported rates in Scandinavia. It is frequently associated with polymyalgia rheumatica, with which it shares epidemiological features.

Evidence & guidelines

The 2022 ACR/EULAR classification criteria define giant cell arteritis for study purposes using clinical, laboratory, imaging, and biopsy items, and EULAR has issued recommendations for the management of large-vessel vasculitis. These documents are summarized here for orientation and are not reproduced as treatment protocols.

History

Although descriptions of cranial arteritis appeared earlier, Bayard Horton and colleagues at the Mayo Clinic gave a detailed clinicopathologic account in the 1930s, after which the disease became known by the eponym Horton disease and the term temporal arteritis entered wide use; later work clarified its overlap with polymyalgia rheumatica and its frequent large-vessel and aortic involvement.

Debates

Biopsy versus imaging for diagnosis

Temporal artery biopsy has long been the diagnostic reference standard, but ultrasonography, MRI, and PET increasingly contribute to recognizing cranial and large-vessel disease, and the optimal role of imaging relative to biopsy continues to be defined.

Key figures

• Bayard Taylor Horton
• Cornelia Weyand
• Jörg Goronzy

Seminal works

• weyand-2014-gca
• ponte-2022-gca-criteria

Frequently asked questions

Why is giant cell arteritis also called temporal arteritis?

Because the temporal arteries are among the cranial vessels it characteristically inflames, producing scalp tenderness and headache; however, the disease frequently involves other large arteries and the aorta, so giant cell arteritis is the broader and now preferred term.

How is giant cell arteritis related to polymyalgia rheumatica?

The two conditions overlap substantially: many people with giant cell arteritis also have polymyalgia rheumatica, and the two are considered closely related disorders of older adults that share epidemiological and inflammatory features.