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

Medium & Variable-Sized Vasculitis for USMLE Step 1

Free One-Month! Institutional (.edu or .org) email required
Log in or start your One-Week Free Trial!
Medium & Variable-Sized Vasculitis for the USMLE Step 1 Exam
Medium and Variable-Sized Vessel Vasculitis
Medium and variable-sized vessel vasculitis includes Polyarteritis Nodosa (PAN), Kawasaki Disease, Thromboangiitis Obliterans (Buerger’s Disease), and Behçet’s Disease. These diseases involve inflammation in medium-sized arteries, and in some cases, both large and small vessels.
    • --
Polyarteritis Nodosa (PAN)
  • Definition:
    • PAN is a necrotizing vasculitis of medium-sized arteries that spares small vessels and is associated with systemic inflammation and tissue ischemia.
  • Epidemiology:
    • Typically affects adults, more common in men; can be associated with hepatitis B infection in some cases.
  • Pathophysiology:
    • Inflammatory damage to arterial walls leads to fibrinoid necrosis, microaneurysm formation, and ischemia in organs such as the kidneys, nerves, and gastrointestinal tract.
  • Clinical Presentation:
    • Systemic: Fever, weight loss, and fatigue.
    • Renal: Hypertension and renal infarction without glomerulonephritis.
    • Neurologic: Mononeuritis multiplex, presenting as asymmetric motor and sensory deficits.
    • Gastrointestinal: Abdominal pain, often postprandial, and risk of bowel infarction.
    • Dermatologic: Livedo reticularis, subcutaneous nodules, and ulcerations.
Polyarteritis Nodosa
  • Diagnosis:
    • Laboratory: Elevated ESR and CRP; hepatitis B serologies in HBV-associated PAN.
    • Biopsy: Shows transmural inflammation and fibrinoid necrosis in medium-sized arteries.
    • Angiography: Reveals microaneurysms, especially in mesenteric or renal arteries.
  • Management:
    • Corticosteroids: Mainstay treatment.
    • Cyclophosphamide: Added in severe cases.
    • Antivirals: Used in HBV-associated PAN with corticosteroids.
    • --
Kawasaki Disease
  • Definition:
    • An acute, self-limited vasculitis affecting medium-sized arteries, particularly the coronary arteries, in children.
  • Epidemiology:
    • Primarily affects children under 5 years, especially in Asian populations.
  • Pathophysiology:
    • Likely triggered by an infectious agent in genetically predisposed children, leading to immune-mediated inflammation and coronary artery involvement.
  • Clinical Presentation:
    • Fever: Prolonged, lasting >5 days.
    • Other Signs: Conjunctivitis, “strawberry tongue,” cracked lips, polymorphous rash, extremity erythema/swelling, and cervical lymphadenopathy.
  • Complications:
    • Coronary artery aneurysms can develop if untreated, leading to myocardial infarction.
  • Diagnosis:
    • Clinical criteria: Fever for >5 days plus four of five criteria (conjunctivitis, oral changes, rash, extremity changes, cervical lymphadenopathy).
    • Echocardiography: Monitors for coronary aneurysms.
  • Management:
    • IVIG: Given early to reduce coronary aneurysm risk.
    • Aspirin: High-dose for inflammation, followed by low-dose to prevent thrombosis in aneurysms.
    • --
Thromboangiitis Obliterans (Buerger’s Disease)
  • Definition:
    • A non-atherosclerotic vasculitis of small- and medium-sized arteries and veins, strongly associated with tobacco use.
  • Epidemiology:
    • Affects young male smokers under 45 years.
  • Pathophysiology:
    • Tobacco use triggers immune-mediated endothelial damage, leading to thrombosis, inflammation, and fibrosis in distal vessels.
  • Clinical Presentation:
    • Ischemia: Claudication, rest pain, ulcers, and gangrene in fingers and toes.
    • Raynaud’s Phenomenon: Color changes in response to cold.
    • Migratory Superficial Thrombophlebitis: Red, tender cords along veins.
  • Diagnosis:
    • Angiography: Shows “corkscrew” collaterals in affected vessels.
    • Clinical Diagnosis: Based on smoking history and symptoms.
  • Management:
    • Smoking Cessation: Only effective treatment to prevent progression.
    • Symptomatic Treatment: Analgesics and wound care; amputation may be required in severe cases.
    • --
Behçet’s Disease
  • Definition:
    • A variable-sized vessel vasculitis affecting arteries and veins, with recurrent oral and genital ulcers, uveitis, and skin lesions.
  • Epidemiology:
    • Common in adults from the Middle East and East Asia.
  • Pathophysiology:
    • Thought to involve an abnormal immune response to environmental triggers in genetically predisposed individuals.
  • Clinical Presentation:
    • Oral and Genital Ulcers: Painful and recurrent.
    • Ocular Involvement: Uveitis, which can lead to vision loss.
    • Skin Lesions: Erythema nodosum and acneiform eruptions.
    • Vascular Complications: Venous thrombosis, pulmonary artery aneurysms.
  • Diagnosis:
    • Based on clinical criteria: recurrent oral ulcers plus two of the following: genital ulcers, uveitis, skin lesions, or a positive pathergy test (skin hypersensitivity).
  • Management:
    • Corticosteroids: For acute flares.
    • Immunosuppressants: Azathioprine or cyclosporine for chronic treatment, especially with ocular involvement.
    • --
Key Points
  • Polyarteritis Nodosa (PAN):
    • Necrotizing vasculitis of medium-sized arteries, causing hypertension, neuropathy, and GI ischemia.
    • Diagnosed by biopsy or angiography, treated with corticosteroids and immunosuppressants.
  • Kawasaki Disease:
    • Vasculitis in children with risk of coronary aneurysms.
    • Diagnosed clinically; managed with IVIG and aspirin.
  • Thromboangiitis Obliterans (Buerger’s Disease):
    • Associated with smoking, affects small and medium arteries of extremities, causing ischemia and ulcers.
    • Smoking cessation is essential for management.
  • Behçet’s Disease:
    • Variable vessel vasculitis with recurrent oral/genital ulcers and uveitis.
    • Managed with corticosteroids for flares and immunosuppressants for severe cases.

Related Tutorials