Libman-Sacks endocarditis is the non-infectious endocarditis characteristic of SLE. The vegetations differ from infective endocarditis in which key histopathological feature?
- A Small, sterile, irregular vegetations on both surfaces of valves (not just closure lines) composed of fibrin and immune complexes without significant bacterial colonization ✓
- B Large, bulky vegetations exclusively on the tricuspid valve from intravenous drug use
- C Small, bland fibrin nodules only at valve closure lines (McCallum's patch pattern)
- D Calcified vegetations with psammoma bodies on the mitral valve
Correct answer: A. Small, sterile, irregular vegetations on both surfaces of valves (not just closure lines) composed of fibrin and immune complexes without significant bacterial colonization
Explanation
Libman-Sacks endocarditis in SLE produces small, sterile, irregular flat vegetations that can occur on either surface (atrial or ventricular) of any valve leaflet, not restricted to the closure line. They are composed of platelet-fibrin deposits and immune complex-containing material, driven by antiphospholipid antibodies and endothelial injury. Rheumatic endocarditis produces small verrucae at closure lines; infective endocarditis has large friable vegetations with organisms; Marantic endocarditis occurs in cachexia/malignancy.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
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