USMLE/COMLEX 2 - Large Vessel Vasculitis

Here are key facts for USMLE Step 2 & COMLEX-USA Level 2 from the Large Vessel Vasculitis tutorial, as well as points of interest at the end of this document that are not directly addressed in this tutorial but should help you prepare for the boards. See the tutorial notes for further details and relevant links.

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1. GCA affects women over 50, especially of Northern European descent, and is associated with polymyalgia rheumatica in up to 50% of cases. 2. Classic symptoms include:

• New-onset temporal headache
• Jaw claudication
• Scalp tenderness
• Visual disturbances, especially amaurosis fugax (transient monocular blindness)

3. Fundoscopy may reveal anterior ischemic optic neuropathy. 4. Temporal artery biopsy is diagnostic, showing granulomatous inflammation with giant cells, but do not delay treatment for biopsy. 5. Elevated ESR and CRP are supportive lab findings. 6. Initiate high-dose corticosteroids (e.g., prednisone) immediately to prevent irreversible vision loss. 7. Most commonly affects young women <40, especially of Asian descent. 8. Presents with:

• Decreased or absent pulses
• Blood pressure discrepancy between arms
• Limb claudication
• Carotid or subclavian bruits
• Hypertension from renal artery involvement

9. Diagnosis is made via CT or MR angiography, showing narrowed or occluded large arteries. 10. Treatment is with systemic corticosteroids, similar to GCA.

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1. Both GCA and Takayasu are granulomatous vasculitides of large vessels, affecting the aorta and its major branches. 2. In GCA, inflammation targets branches of the external carotid artery, especially the temporal artery. 3. In Takayasu, inflammation affects the aortic arch and its branches, leading to stenosis and ischemia. 4. Histologically, GCA shows:

• Granulomatous inflammation
• Multinucleated giant cells
• Destruction of the internal elastic lamina
• Intimal hyperplasia

5. Takayasu arteritis shows thickening, fibrosis, and narrowing of large vessels due to chronic inflammation. 6. Polymyalgia rheumatica presents with proximal muscle pain and stiffness, elevated ESR, and rapid response to low-dose steroids. 7. GCA is a major cause of permanent vision loss in the elderly if untreated. 8. Complications of Takayasu include:

• Aortic aneurysm
• Aortic regurgitation
• Renal artery stenosis leading to hypertension
• Retinopathy

9. Temporal artery biopsy may yield false negatives due to segmental involvement, so clinical diagnosis may supersede pathology. 10. Imaging (CT/MRI) is preferred for Takayasu, not temporal biopsy. 11. Monitor treatment response with ESR/CRP trends.

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1. For suspected GCA with visual symptoms, start corticosteroids immediately, even before confirming with biopsy. 2. Methylprednisolone IV is used in severe or vision-threatening GCA cases, then transitioned to oral prednisone. 3. Steroid-sparing agents (e.g., methotrexate or tocilizumab) may be considered for patients with frequent relapses or long-term steroid complications. 4. Ophthalmology consultation is crucial for GCA patients with visual complaints. 5. Vascular surgery or rheumatology referral may be appropriate in Takayasu for severe arterial compromise. 6. Monitor for relapse, steroid side effects, and vascular complications with serial ESR/CRP and imaging. 7. Long-term steroids increase risk of osteoporosis, hyperglycemia, and infection; co-prescribe calcium, vitamin D, and consider bisphosphonates. 8. In Takayasu, BP should be measured in both arms, and renal function monitored closely.