USMLE/COMLEX 1 - Medium & Variable Vessel Vasculitis

Here are key facts for USMLE Step 1 & COMLEX-USA Level 1 from the Medium & Variable Size 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. Vasculitis is characterized by inflammation of blood vessels, leading to necrosis, ischemia, and organ damage. 2. Common systemic symptoms of vasculitis include fever, weight loss, fatigue, arthralgias, and myalgias. 3. Corticosteroids and immunosuppressants are the main treatments for most vasculitides. 4. PAN affects medium-sized muscular arteries, especially at branch points. 5. PAN causes necrotizing inflammation leading to ischemia and multisystem involvement:

• Peripheral nervous system: mononeuritis multiplex (asymmetric neuropathies affecting median, ulnar, fibular nerves)
• Renal system: hypertension, renal insufficiency (without glomerulonephritis)
• GI tract: mesenteric ischemia, pain, malabsorption, aneurysms
• Skin: livedo reticularis, ulcers, nodules, gangrene
• Heart: coronary artery disease leading to heart failure

6. PAN is associated with hepatitis B infection and less commonly hepatitis C. 7. Predominantly affects middle-aged men. 8. Kawasaki disease is a medium vessel vasculitis primarily affecting children under 5 years. 9. It is a major cause of acquired heart disease in children due to risk of coronary artery aneurysms. 10. Diagnostic features include:

• Fever lasting at least 5 days
• Bilateral non-exudative conjunctivitis
• Oral mucosal changes (strawberry tongue, fissured lips)
• Polymorphous rash
• Peripheral extremity changes (edema, erythema, desquamation)
• Cervical lymphadenopathy

11. Laboratory findings: elevated ESR, CRP, thrombocytosis, leukocytosis, sterile pyuria, elevated liver enzymes, hypoalbuminemia. 12. Treatment is with high-dose IVIG and aspirin to prevent coronary complications.

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1. Behçet disease is a vasculitis of all vessel sizes characterized by recurrent oral and genital ulcers, uveitis, and skin lesions (erythema nodosum, papulopustular lesions). 2. Hypopyon (layering of pus in anterior chamber of the eye) may be present. 3. Disease is more severe in men, and typically presents around age 20. 4. Buerger disease is a small and medium vessel vasculitis strongly associated with smoking. 5. Involves distal extremities (hands and feet) and causes:

• Claudication (pain with exercise)
• Rest pain
• Cold sensitivity
• Cyanosis
• Ulceration leading to gangrene

6. Histology: neutrophilic infiltration and granulomatous inflammation causing occlusion without significant destruction of vessel wall. 7. Corkscrew collaterals on arteriography are characteristic. 8. Smoking cessation is critical for treatment and disease remission. 9. In general, vasculitides cause tissue ischemia through inflammation, thrombosis, and direct vessel damage. 10. Medium-vessel vasculitis typically targets muscular arteries and presents with end-organ ischemia rather than glomerulonephritis (seen in small vessel vasculitis).

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1. PAN spares the pulmonary arteries, distinguishing it from other vasculitides like GPA (granulomatosis with polyangiitis). 2. ANCA negative: PAN is typically negative for anti-neutrophil cytoplasmic antibodies (ANCA). 3. Coronary aneurysms are the most feared complication; all patients require echocardiographic monitoring. 4. Beau’s lines (transverse grooves in fingernails) may occur during recovery. 5. Risk of thrombosis or myocardial infarction exists if aneurysms develop. 6. Often associated with HLA-B51 genetic marker. 7. Pathergy test (development of papule at site of needle stick) may be positive. 8. Often found in young male smokers under age 45. 9. Can coexist with Raynaud phenomenon due to distal vessel sensitivity.