What is the histology of infective endocarditis vegetations?

What is the histology of infective endocarditis vegetations?

• A. Fibrin-platelet aggregates with organisms on valve leaflets; vegetations on the lines of closure; possible destruction
• B. Calcification of valve leaflets
• C. Fibroelastic thickening without organisms
• D. Pure inflammatory infiltrates with no organisms

Answer: (A)

Infective endocarditis vegetations are best understood as fibrin-platelet aggregates deposited on the valve surface that trap and harbor microorganisms. The endocardial surface is damaged by turbulent flow, so a thrombus forms along the line of closure, and bacteria or other pathogens colonize this thrombus, often with inflammatory cells mingled in. This combination—a friable, fibrin-rich mass with microbial colonies on a valve leaflet—is why the histology shows organisms embedded in a fibrin-platelet vegetations, and why destruction of valve tissue and risk of embolization can occur. By comparison, calcification of valve leaflets reflects degenerative or age-related changes, fibroelastic thickening without organisms points to noninfectious valvular disease such as rheumatic or degenerative processes, and pure inflammatory infiltrates with no organisms fit noninfectious endocarditis scenarios rather than infective ones.

Infective endocarditis vegetations are best understood as fibrin-platelet aggregates deposited on the valve surface that trap and harbor microorganisms. The endocardial surface is damaged by turbulent flow, so a thrombus forms along the line of closure, and bacteria or other pathogens colonize this thrombus, often with inflammatory cells mingled in. This combination—a friable, fibrin-rich mass with microbial colonies on a valve leaflet—is why the histology shows organisms embedded in a fibrin-platelet vegetations, and why destruction of valve tissue and risk of embolization can occur. By comparison, calcification of valve leaflets reflects degenerative or age-related changes, fibroelastic thickening without organisms points to noninfectious valvular disease such as rheumatic or degenerative processes, and pure inflammatory infiltrates with no organisms fit noninfectious endocarditis scenarios rather than infective ones.