4.02 Medium Vessel Vasculitis

Rheumatology review for the USMLE Step 1 exam.

• Vasculitis: inflammation of blood vessels, classified by the size of the blood vessels affected
• Medium vessel vasculitis affects the main visceral arteries and veins, and their initial branches
• Three types of medium vessel vasculitis are discussed: polyarteritis nodosa, Kawasaki disease (mucocutaneous lymph node syndrome), and Buerger disease (thromboangiitis obliterans)
• Polyarteritis nodosa affects middle-aged to older men and is idiopathic, but can be secondary to other diseases, including hepatitis B
• Histology findings show transmural inflammation with fibrinoid necrosis in early lesions, and string-of-beads sign in angiogram
• Symptoms include constitutional symptoms, abdominal pain and melena, and hypertension caused by damage to the renal arteries
• Kawasaki disease most commonly affects young Asian children, and is triggered by upper airway infections
• Symptoms include conjunctival injection, desquamating rash, cervical lymphadenopathy, strawberry tongue, and prolonged fever
• Kawasaki disease has a predilection for the coronary vessels, which can lead to aneurysm rupture and thrombi development
• Treatment for Kawasaki disease includes IVIG and aspirin to prevent complications