Back
ditki Logo
medical & biological sciences
All Access Pass - 1 FREE Month!
Institutional email required, no credit card necessary.

Large Vessel Vasculitis for USMLE Step 3

Free One-Month! Institutional (.edu or .org) email required
Log in or start your One-Week Free Trial!
Large Vessel Vasculitis for the USMLE Step 3 Exam
Large Vessel Vasculitis
Large vessel vasculitis includes two main types: Giant Cell Arteritis (GCA) and Takayasu Arteritis (TA), both characterized by inflammation of the aorta and its major branches. These conditions vary in clinical presentation, demographic prevalence, and management strategies.
    • --
Giant Cell Arteritis (GCA)
  • Definition:
    • Also known as temporal arteritis, GCA affects the aorta and its branches, particularly the cranial arteries, including the temporal arteries.
    • Often associated with polymyalgia rheumatica (PMR), presenting in older adults.
Large vessel vasculitis vessels
  • Epidemiology:
    • Primarily affects adults over 50 years, with a higher incidence in women and individuals of Northern European descent.
  • Pathophysiology:
    • Granulomatous inflammation in the vessel wall, characterized by giant cells, leads to luminal narrowing and ischemia.
    • Immune cell infiltration damages the vessel wall, causing thickening and potential occlusion, especially affecting cranial arteries.
  • Clinical Presentation:
    • Systemic Symptoms: Fatigue, weight loss, and fever.
    • Headache: Severe, localized to the temporal area with scalp tenderness.
    • Jaw Claudication: Pain in the jaw muscles while chewing, a classic symptom.
    • Visual Disturbances: Transient vision loss (amaurosis fugax), which can lead to blindness if untreated.
    • Polymyalgia Rheumatica (PMR): Commonly coexists with GCA, causing pain and stiffness in the shoulders and hips.
  • Diagnosis:
    • Elevated ESR and CRP: Highly sensitive markers for GCA.
    • Temporal Artery Biopsy: Gold standard, showing mononuclear cell infiltration and giant cells.
    • Imaging: Doppler ultrasound may show a “halo sign” around inflamed temporal arteries; MRI or CT angiography assesses aortic involvement.
  • Management:
    • Corticosteroids: High-dose prednisone (40-60 mg/day) is the primary treatment to prevent ischemic complications, especially vision loss.
    • Tocilizumab: IL-6 receptor antagonist approved for GCA, often used in cases with relapsing disease or to reduce steroid dependence.
    • Aspirin: Low-dose aspirin may be used to decrease thrombotic risks.
    • --
Takayasu Arteritis (TA)
  • Definition:
    • Takayasu arteritis is a granulomatous vasculitis affecting the aorta and its branches, often resulting in segmental stenosis, occlusion, or aneurysms.
    • Sometimes called “pulseless disease” due to diminished pulses in affected areas.
  • Epidemiology:
    • Primarily affects women under 40, with a higher incidence in Asian and Latin American populations.
  • Pathophysiology:
    • Similar to GCA, TA involves granulomatous inflammation in the vessel wall, leading to fibrosis, stenosis, and arterial occlusion.
    • Chronic inflammation results in vascular remodeling and fibrosis, which can cause segmental narrowing or aneurysms.
  • Clinical Presentation:
    • Systemic Symptoms: Fatigue, fever, weight loss.
    • Vascular Symptoms:
    • Upper Limb Claudication: Pain and fatigue in the arms due to ischemia.
    • Diminished Pulses and Bruits: Weak or absent pulses in the arms and neck; bruits over affected arteries.
    • Blood Pressure Discrepancies: Significant differences between arms due to subclavian artery stenosis.
    • Hypertension: Often secondary to renal artery stenosis, leading to renovascular hypertension.
  • Diagnosis:
    • Elevated ESR and CRP: Markers of systemic inflammation.
    • Imaging:
    • MRI Angiography (MRA) and CT Angiography (CTA): Key imaging studies for detecting stenosis, occlusion, and aneurysms.
    • Conventional Angiography: Less commonly used but provides detailed visualization of arterial lesions.
  • Management:
    • Corticosteroids: Prednisone (1 mg/kg/day) is first-line therapy, followed by a gradual taper.
    • Immunosuppressive Agents: Methotrexate, azathioprine, or mycophenolate mofetil for patients with refractory disease or as steroid-sparing agents.
    • Biologics: Tocilizumab and TNF-alpha inhibitors may be used in resistant cases.
    • Revascularization: Angioplasty or surgical intervention may be necessary in cases of severe stenosis or organ-threatening ischemia.
    • --
Key Points
  • Giant Cell Arteritis (GCA):
    • Commonly affects adults >50 years, presenting with temporal headache, jaw claudication, visual disturbances, and association with polymyalgia rheumatica.
    • Diagnosis relies on elevated ESR/CRP and temporal artery biopsy; high-dose corticosteroids are essential for preventing vision loss.
  • Takayasu Arteritis (TA):
    • Primarily affects young women, especially of Asian or Latin American descent.
    • Presents with limb claudication, diminished pulses, blood pressure discrepancies, and hypertension.
    • Diagnosed through MRA or CTA imaging; managed with corticosteroids and immunosuppressants.
  • Similarities and Differences:
    • Both GCA and TA involve granulomatous inflammation but differ in age of onset and vessel locations.
    • Corticosteroids are the main treatment; tocilizumab is a steroid-sparing option for refractory cases.
  • Complications:
    • GCA: Vision loss, aortic aneurysms.
    • TA: Severe hypertension, limb ischemia, and aortic aneurysms or dissections requiring monitoring and potential intervention.

Related Tutorials