A 25-year-old tall, thin man has a midsystolic click and late systolic murmur. Echocardiography shows billowing of both mitral leaflets into the left atrium during systole. The characteristic microscopic change in the valve leaflets is:

• A Fibrosis and commissural fusion with calcification
• B Myxomatous degeneration with expansion of the spongiosa layer ✓
• C Neovascularisation and inflammation of the fibrosa
• D Mucoid degeneration confined to the chordae tendineae only

Explanation

Mitral valve prolapse shows myxomatous degeneration: accumulation of acid mucopolysaccharide-rich ground substance that expands the middle spongiosa layer of the leaflet, thins the fibrosa and allows systolic prolapse. Commissural fusion and calcification belong to chronic rheumatic mitral disease, while neovascularised inflamed valves suggest healed infective endocarditis. Elongated chordae may accompany the process but are not the defining lesion.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.