Giant Cell Arteritis (GCA)

Risk factors

• Age >50
• Female sex
• Northern European ancestry
• HLA-DR4
• Polymyalgia rheumatica
• Smoking (modest association)

Pathophysiology

Cell-mediated immune response to arterial wall antigens drives granulomatous inflammation centered on the internal elastic lamina. Multinucleated giant cells, lymphocytes, and macrophages cause intimal hyperplasia and luminal narrowing. The ophthalmic artery and posterior ciliary arteries supply the optic nerve head — their occlusion causes anterior ischemic optic neuropathy and permanent vision loss.

Clinical presentation

Differential diagnosis

• Tension or migraine headache — Younger patients, no constitutional symptoms, normal ESR/CRP
• Trigeminal neuralgia — Lancinating facial pain in trigeminal distribution; not a continuous temporal ache
• Takayasu arteritis — Large-vessel vasculitis in patients <40, predominantly women; aortic arch involvement with diminished pulses
• Non-arteritic anterior ischemic optic neuropathy (NAION) — Painless monocular vision loss without systemic symptoms; normal ESR/CRP; small crowded discs
• Retinal vascular occlusion — Sudden painless vision loss; fundoscopic findings distinguish; check carotid sources
• Sinusitis, TMJ disorder — Localized facial pain or pressure; imaging or dental evaluation clarifies
• Other vasculitides (ANCA-associated, PAN) — Multisystem features, ANCA testing, characteristic organ involvement

Diagnostic workup

Diagnostic algorithm

flowchart TD
  A[Adult >50<br/>new headache, jaw claudication,<br/>visual Sx, scalp tenderness] --> B[Check ESR and CRP<br/>start prednisone immediately]
  B --> C{Visual<br/>symptoms?}
  C -->|Yes| D[IV methylprednisolone<br/>500-1000 mg x 3 days]
  C -->|No| E[Prednisone<br/>40-60 mg/day]
  D --> F[Transition to high-dose<br/>oral prednisone]
  E --> G[Temporal artery biopsy<br/>or ultrasound within 2 weeks]
  F --> G
  G --> H{Diagnosis<br/>confirmed?}
  H -->|Yes| I[Slow taper over 12-24 months<br/>+ tocilizumab steroid-sparing<br/>+ aspirin + bone protection]
  H -->|No, low suspicion| J[Taper steroids<br/>seek alternative dx]

Treatment

Complications

• Permanent monocular or binocular vision loss (irreversible once established) — the most feared complication
• Stroke (vertebrobasilar more than carotid territory)
• Thoracic aortic aneurysm and dissection (years after initial presentation — long-term imaging surveillance)
• Limb ischemia, mesenteric ischemia
• Steroid toxicity: osteoporosis, diabetes, infection, weight gain
• Relapse during taper (very common)

PANCE pearls

• When GCA is suspected, treat first and biopsy within 2 weeks — never delay steroids for biopsy.
• Jaw claudication is one of the most specific historical findings; ask explicitly.
• Normal ESR does not exclude GCA — about 4% of biopsy-proven cases have ESR <50; CRP adds sensitivity.
• Patients with GCA have an elevated lifetime risk of thoracic aortic aneurysm — periodic imaging is warranted.
• Tocilizumab is now first-line steroid-sparing therapy.

References

• ACR/EULAR 2022 — 2022 ACR/EULAR Classification Criteria for Giant Cell Arteritis (Ponte et al., Ann Rheum Dis 2022)
• ACR/VF 2021 — 2021 ACR/VF Guideline for the Management of GCA and Takayasu Arteritis (Maz et al., Arthritis Rheumatol 2021)