Giant Cell Arteritis - Temporal Arteritis

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

Which testing algorithms are related to this topic?

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

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%

Differential Diagnosis

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 first-line reflex panel for the evaluation of ANCA-associated vasculitis

Components: ANCA, IgG; myeloperoxidase antibody; and serine proteinase 3 antibody

Preferred test to detect acute phase inflammation (eg, autoimmune diseases, connective tissue disease, rheumatoid arthritis, infection, or sepsis)

Related Tests

Initial screening for hepatobiliary inflammation

Panel includes albumin; alkaline phosphatase (ALP); aspartate aminotransferase (AST); alanine aminotransferase (ALT); bilirubin, direct; protein, total; and bilirubin, total

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