In non-bacterial thrombotic endocarditis (NBTE, marantic endocarditis), vegetations are characteristically located on which valve surface and composed of which material?

• A Tricuspid valve, exclusively; infected vegetations containing Gram-negative rod bacteria associated with IV drug use
• B Mitral valve posterior leaflet, atrial surface; vegetations with giant cells and calcification in rheumatic heart disease
• C Mitral/aortic valve, line of closure on the atrial/ventricular side; sterile fibrin-platelet vegetations without inflammatory cells or organisms, associated with hypercoagulable states and malignancy ✓
• D Aortic valve, ventricular surface; bland fibrin deposits without thrombogenesis seen in Libman-Sacks endocarditis

Explanation

NBTE (marantic endocarditis) features small, bland, sterile vegetations along the line of valve closure on the atrial surface of AV valves (mitral > tricuspid) and ventricular surface of semilunar valves (aortic, pulmonic). The vegetations consist of fibrin and platelets with virtually no inflammatory cells and no microorganisms, distinguishing them from infective endocarditis. NBTE is associated with hypercoagulable states, advanced malignancy (particularly mucinous adenocarcinomas that activate coagulation via mucin-associated tissue factor), prolonged debilitating illness, and SLE. The danger of NBTE is systemic embolization causing strokes and organ infarcts. Tricuspid infective endocarditis in IV drug users involves bacteria (commonly Staphylococcus aureus). Libman-Sacks endocarditis (in SLE) affects both surfaces of mitral leaflets.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.