Giant cell arteritis (temporal arteritis) is a systemic vasculitis that can produce permanent blindness if not treated in a timely manner. It is categorized as a large-vessel vasculitis (Chapel Hill 2012).
Quick Answers for Clinicians
Diagnosis
Indications for Testing
- Patient >50 years with
- Visual changes or new onset localized headache
- Elevated inflammatory marker(s)
Criteria for Diagnosis
Histologic diagnosis – temporal artery biopsy showing segmental inflammation
Laboratory Testing
- Nonspecific testing – helpful in excluding other diagnoses
- CBC – thrombocytosis, normochromic normocytic anemia
- C-reactive protein (CRP)
- Erythrocyte sedimentation rate (ESR) – has been used traditionally with threshold of >50 mm/hr
- Liver function studies – often abnormal
- Vasculitis evaluation
- Antineutrophil cytoplasmic antibodies (ANCA) – high percentage have perinuclear ANCA (pANCA) with MPO+
- Proteinase 3 (PR3) rarely positive
- Antineutrophil cytoplasmic antibodies (ANCA) – high percentage have perinuclear ANCA (pANCA) with MPO+
Histology
- Temporal artery biopsy – demonstrates medium- and large-vessel vasculitis with giant cell infiltration
- 1.5-2 cm long biopsy is recommended due to possibility of skip lesions
- Biopsy should be performed before day 4 if steroid therapy initiated
- If initial biopsy is negative, perform biopsy on other side
Imaging Studies
- Duplex ultrasonography
- Halo sign is often present
- Defined as hypoechoic region around the lumen of the artery
- Sensitivity – <70%
- Halo sign is often present
Differential Diagnosis
- Infectious
- Malignancy (eg, multiple myeloma)
- Connective tissue disease
- Fibromyalgia
- Statin therapy myopathy
- Osteoarthritis
- Other vasculitic disease
- Granulomatosis with polyangiitis (formerly Wegener granulomatosis)
- Eosinophilic granulomatosis with polyangiitis (formerly Churg-Strauss syndrome)
- Microscopic polyangiitis
- Polyarteritis nodosa
Background
Epidemiology
- Prevalence – ~20/million in U.S.; most common primary vasculitis in older patients
- Age – peak age 70-80 years
- Rare – <50 years
- Sex – M<F, 1:2-6
- Ethnicity – more common in Caucasians than African or Asian Americans; rare in Hispanic population (Weyand, 2014)
Pathophysiology
- Medium- and large-vessel vasculitis – tends to affect aorta and extracranial branches of the carotid artery
- Vasculitis causes ischemic disease – most common in the optic nerve
- Can lead to vision loss, caused primarily by occlusive vasculopathy
- Granulomas form in arterial media
- Often associated with polymyalgia rheumatica
Clinical Presentation
- Constitutional – fever, fatigue, malaise, weight loss
- Otorhinologic – jaw claudication
- Ophthalmologic – transient visual changes, diplopia, visual field cuts, permanent vision loss
- Cardiovascular – arm claudication, thoracic artery aneurysm
- Neurologic – headache, temporal artery pain, mononeuropathy
- Polymyalgia rheumatica – may occur in up to 50% of patients
- Manifests with severe stiffness and pain in shoulders, thighs, and buttocks
- Dermatologic, renal, pulmonary – rarely involved
ARUP Laboratory Tests
Preferred reflex panel for managing patients with a known diagnosis of vasculitis
May be assistive in evaluating suspected vasculitis
For the workup of suspected vasculitis, the preferred reflex panel is ANCA-associated vasculitis profile (ANCA/MPO/PR3) with reflex to ANCA titer
Semi-Quantitative Indirect Fluorescent Antibody/Semi-Quantitative Multiplex Bead Assay
Preferred test to detect acute phase inflammation (eg, autoimmune diseases, connective tissue disease, rheumatoid arthritis, infection, or sepsis)
Quantitative Immunoturbidimetry
Nonspecific test used to detect inflammation associated with infections, cancers, and autoimmune diseases
Visual Identification
May help in ruling out infectious process
Automated Cell Count/Differential
Initial screening for hepatobiliary inflammation
Quantitative Enzymatic/Quantitative Spectrophotometry
Panel includes albumin; alkaline phosphatase (ALP); aspartate aminotransferase (AST); alanine aminotransferase (ALT); bilirubin, direct; protein, total; and bilirubin, total
Screens for various metabolic and kidney disorders
Reflectance Spectrophotometry/Microscopy
Medical Experts
Tebo

References
Choosing Wisely
Choosing Wisely. An initiative of the ABIM Foundation. [Accessed: Dec 2020]
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Jennette JC, Falk RJ, Bacon PA, et al. 2012 revised International Chapel Hill Consensus Conference nomenclature of vasculitides. Arthritis Rheum. 2013;65(1):1-11.
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Nusser JA, Howard E, Wright D. Clinical inquiries. Which clinical features and lab findings increase the likelihood of temporal arteritis? J Fam Pract. 2008; 57 (2): 119-20.
Panel includes ANCA, IgG; myeloperoxidase antibody; and serine proteinase 3 antibody