Overview

• Large vessel vasculitides involve the aorta and its large branches.
• Vasculitides of all sizes are characterized by blood vessel inflammation, sometimes with necrosis, and can lead to ischemia and organ damage.
• Vessels and organs affected vary by the specific vasculitic disorder.
• General symptoms and signs of vasculitides are due to systemic inflammation, including fever, arthritis, arthralgia, fatigue, and weight loss. As we’ll see, specific end-organ damage varies by the vessels affected.
• Typical treatment includes corticosteroids and immunosuppressants.

Giant Cell Arteritis aka, temporal arteritis or Horton disease.

• It is a granulomatous disease.
• It specifically affects the aorta and its large branches, especially the external carotid arteries.
  – Thus, affected vessels include those of the head and neck, such as the superficial temporal artery, which is commonly involved.
• Common symptoms include:
  – Raised, tender temporal artery, which is sometimes visible on the patient’s forehead
  – Vision loss
  – Neck and/or jaw pain
  – Tongue necrosis
• Indicate that giant cell arteritis is most common in women over 55 years of age, and especially those of Northern European descent.
• It is associated with polymyalgia rheumatica in up to 50% of cases.
• Serious complications include aortic aneurysm, stroke, and blindness; thus, treatment should be provided as soon as possible.

Histopathology:

We show a normal large artery, for comparison.

• Giant cell arteritis
  – Key elements of the pathogenesis of giant cell arteritis, according to a very generalized model.
  Dendritic cells in the adventitia are activated, perhaps by viruses or other stimuli;
  Activated dendritic cells recruit and activate CD4+ T cells
  CD4+ T cells release pro-inflammatory cytokines and recruit and activate pro-inflammatory macrophages.
  Macrophages secrete growth factors and facilitate migration and proliferation of vascular smooth muscle cellswithin the intima, *which promotes its hyperplasia.
  Additionally, the macrophages form multinucleated giant cells, which secrete various harmful substances, such as ROS, NO, and matrix metalloproteinases (MMP), which destroys the tunica media and internal elastic lamina.
  – In summary, the histopathology of giant cell arteritis is characterized by:
  Chronic inflammation
  Granuloma formation
  Destruction of the tunica media and elastic laminae
  Tunica intima remodeling and hyperplasia
  Lumen occlusion – which, as we’ve seen, can lead to downstream ischemia and tissue damage.

Takayasu arteritis, aka, pulseless disease

• A granulomatous disease that affects the aorta and its large branches.
• Thickening and fibrosis of the vessel walls narrows the lumen.
  – In the image, we can see the large, bulging aorta and the aortic arch branches.
• The resulting ischemia produces:
  – A weak or absent pulse in the extremities (hence the alternative name, “pulseless disease”)
  – Different blood pressures in the upper extremities (that is, right vs. left), and vascular bruits
  – Claudication in the limbs
  – Chest pain
  – And, possible hypertension, due to renal artery stenosis.
• Possible complications include aneurysm, aortic regurgitation, and retinopathy.
• Takayasu arteritis is most common in women younger than 40 years old, and seems to be more common in women of Asian descent.