83: GIANT CELL AND TAKAYASU ARTERITIS

PATIENT STORY

A 68-year-old woman presented to the hospital with a 2-day history of left-eye blindness and a discolored lower lip and tongue. One week prior she presented to her dentist complaining her dentures were not fitting correctly and was treated for thrush. She was previously in good health and never had visual or oral complaints.

Figures 83-1 and 83-2 demonstrate how giant cell arteritis (GCA) can present with nonspecific findings yet cause significant ischemia and organ damage. Below is a comparison demonstrating how GCA and Takayasu arteritis (TA) are points on a continuum of an inflammatory clinical process differing by age of onset, pathogenic mechanism, and the vascular beds commonly affected.

EPIDEMIOLOGY

Giant Cell Arteritis

• Increasing frequency with age and average age of diagnosis 72 years.¹

• Women are more likely affected than men.²

• Prevalence up to 1 in 500 among individuals older than 50 years.²

• Northern European ancestry living in the United States or Europe.³

• History of smoking and atheromatous disease increase risk in women.⁴

• Human leukocyte antigen (HLA)-DR4 positivity.⁴

Takayasu Arteritis

• 80% to 90% of cases are in women between the ages of 10 and 40.

• Greatest prevalence in Asia. Japan reports 150 new cases per year compared to one to three new cases per million people in the United States and Europe.⁵

• Additional risk factors: HLA-B52, HLA-B39 positivity.

ETIOLOGY AND PATHOPHYSIOLOGY

Giant Cell Arteritis

• The pathogenic mechanism of GCA is unknown. However, current understanding implicates a foreign antigen in a cascade of events that under-standing results in arterial inflammation.

  • An antigenic stimulant activates dendritic cells, which in turn activate CD4 T lymphocytes that produce interferon-gamma (INF-γ), which has significant effects on macrophage activation and function.

  • This leads to further cytokine and chemokine production, especially interleukin 1 (IL-1), IL-6, transforming growth factor, and monocyte chemoattractant protein 1 (MCP-1).

  • These processes cause immune activation in the adventitia, which ultimately leads to inflammatory changes including granuloma formation, multinucleated giant cells, growth factors, and reactive oxygen intermediates.

  • This entire process subsequently leads to remodeling of the luminal wall caused by matrix digestion, smooth muscle loss, proliferation of myofibroblast, and intimal hyperplasia.

  • All of the above processes contribute to luminal occlusion.

Takayasu Arteritis

• The etiology and pathogenesis of TA remains unknown, but ...