Giant Cell Arteritis - Temporal Arteritis

Diagnosis

Indications for Testing

  • Patient >50 years with visual changes or new onset headache

Criteria for Diagnosis

  • American College of Rheumatology (1990); 3 of 5 required
    • Age – >50 years
    • New localized headache
    • Temporal artery tenderness or decreased pulsation
    • ESR – >50 mm/hr
    • Abnormal arterial artery biopsy

Laboratory Testing

  • Nonspecific testing
    • CBC –  may have platelet count >375,000 (L.R. 6.0); normochromic normocytic anemia
    • ESR/CRP – elevated; if both are elevated, sensitivity of diagnosis increased to 99%
      • ESR usually exceeds 50 mm/hr and may exceed 100 mm/hr (L.R. 2.5)
    • Liver function studies – often abnormal
  •  Testing for vasculitis
    • ANCA – 75% have pANCA with MPO+
      • PR3 rarely positive

Histology

  • Temporal artery biopsy – medium- and large-vessel vasculitis with giant cell infiltration
    • May have skin lesions; therefore, 2 cm long biopsy is recommended
  • Biopsy should be performed before day 4 of steroid therapy
  • 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 

Clinical Background

Giant cell arteritis, also known as temporal arteritis, is a systemic vasculitis that can produce permanent blindness if not treated in a timely manner.

Epidemiology

  • Incidence – 18-22/1,000,000 in U.S.; most common primary vasculitis in older patients
  • Age – almost exclusively >50 years; peak age 70-80 years
  • Sex – M<F, 1:2-6
  • Ethnicity – more common in Caucasians than African Americans; rare in Hispanic population

Pathophysiology

  • Medium- and large-vessel vasculitis – tends to affect aorta and extracranial branches of the carotid artery
  • 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 (L.R. 4.0)
  • Ophthalmologic – transient visual changes, diplopia (L.R. 3.4), visual field cuts, permanent vision loss
  • Cardiovascular – arm claudication, thoracic artery aneurysm
  • Neurologic – headache, temporal artery pain (L.R. 2.0), mononeuropathy
  • Polymyalgia rheumatica – symptoms occur in up to 50% of patients
    • Manifests with severe stiffness and pain in shoulders, thighs, and buttocks

Treatment

  • Steroids – first-line therapy
  • May require addition of other immunosuppressives in order to taper steroids

Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
CBC with Platelet Count and Automated Differential 0040003
Method: Automated Cell Count/Differential
Order to differentiate between infectious and noninfectious process    
Sedimentation Rate, Westergren (ESR) 0040325
Method: Visual Identification

Use to assess for inflammation

   
C-Reactive Protein 0050180
Method: Quantitative Immunoturbidimetry

Use to assess for inflammation

   
Hepatic Function Panel 0020416
Method: Quantitative Enzymatic/Quantitative Spectrophotometry

Use to assess for liver function abnormalities

   
Anti-Neutrophil Cytoplasmic Antibody with Reflex to Titer and MPO/PR-3 Antibodies 2002068
Method: Semi-Quantitative Indirect Fluorescent Antibody/Semi-Quantitative Multiplex Bead Assay

Test for vasculitis

If screen is positive, titer and MPO/PR-3 antibodies testing will be added to aid in antibody determination