• Clinical science

Giant cell arteritis (Temporal arteritis…)

Summary

Giant cell arteritis (GCA) is a type of autoimmune vasculitis that causes chronic inflammation of large and medium-sized arteries, in particular the carotid arteries, its major branches, and the aorta. It is most common in white women over the age of 50, and approximately 50% of patients also have polymyalgia rheumatica. Patients usually present with constitutional symptoms (e.g., fever, weight loss, night sweats, fatigue, and malaise), new-onset headache, a tender, hardened temporal artery, jaw claudication, or amaurosis fugax. Laboratory tests typically show signs of inflammation (e.g., elevated erythrocyte sedimentation rate and CRP), and temporal artery biopsy should be performed to confirm the diagnosis. The classic histopathological findings are mononuclear infiltration of the vessel wall and formation of giant cells. If GCA is suspected, prompt administration of glucocorticoids is essential to reduce the risk of permanent vision loss and cerebral ischemia.

Epidemiology

  • Sex: >
  • Peak incidence: 70–79 years; rarely seen in patients < 50 years
  • Most common among individuals of northern European descent

Women of advanced age are particularly prone to the disease!
References:[1][2]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

  • Unknown; possible contributing factors include:
  • Association with polymyalgia rheumatica (PMR): 40–50% of patients with giant cell arteritis also have PMR.

References:[1][2]

Pathophysiology

Giant cell arteritis is thought to be due to a cell-mediated immune response to endothelial injury. However, the initiating factors are not fully understood.

  1. Inflammation
    • Activation of dendritic cells in the adventitia of blood vessel walls → Dendritic cells recruit Th1 cells, CD8+ T cells, and monocytes.
    • Monocytes differentiate to macrophages and giant cells, which produce cytokines (e.g., IL-6, TNF-α) that augment the inflammatory response.
  2. Local vascular damage: macrophages produce metalloproteinases → destruction of vessel wall structures (e.g., internal elastic lamina)
  3. Concentric intimal hyperplasia: macrophages and giant cells produce PDGF and VEGF → stimulate intimal proliferation → reduced blood flow and ischemia

References:[1]

Clinical features

  • Constitutional symptoms
    • Fever, weight loss, night sweats
    • Symptoms of anemia: fatigue and malaise
  • Symptoms of arterial inflammation: extracranial branches of the common carotid, internal carotid, and external carotid arteries (the temporal artery is the most commonly affected vessel)
  • Vision loss
  • Diplopia
  • Symptoms of polymyalgia rheumatica (if both diseases are present)

About 50% of patients with giant cell arteritis also have polymyalgia rheumatica!

References:[1][2]

Diagnostics

  • ACR criteria (3 of the 5 criteria are required)
    1. Age at disease onset ≥ 50 years
    2. Headaches
    3. Abnormalities of the temporal artery
    4. Elevated ESR (≥ 50 mm/h; see “Laboratory tests” below)
    5. Histopathological abnormalities in the temporal artery (see “Temporal artery biopsy” below)
  • Laboratory tests
  • Temporal artery biopsy (gold standard): mandatory in all patients
    • Extended biopsy sample (≥ 1 cm, ideally ≥ 2 cm)
    • Specificity: 100%
  • Duplex ultrasonography
    • Hourglass deformity
    • Halo sign

References:[1][2][3][4][5]

Pathology

References:[1]

Differential diagnoses

References:[6][1][2]

The differential diagnoses listed here are not exhaustive.

Treatment

Immediate administration of high-dose glucocorticoids is crucial to prevent permanent vision loss in patients with giant cell arteritis!
References:[7][1][8][9]

Complications

  • Permanent vision loss: ∼ 20–30% if giant cell arteritis is left untreated
  • Cerebral ischemia (e.g., transient ischemic attack and stroke): < 2% of cases
  • Aortic aneurysm and/or dissection: ∼ 10–20% of patients

References:[7][9]

We list the most important complications. The selection is not exhaustive.