Giant Cell Arteritis - Temporal Arteritis

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

• Infectious
  • Virus
  • Hepatitis A, B, C
  • HIV
  • Endocarditis
• Malignancy (eg, multiple myeloma)
• Connective tissue disease
  • Systemic lupus erythematosus (SLE)
  • Inflammatory myopathies
  • Rheumatoid arthritis
• 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