A 24-year-old tall man with arm span greater than height develops sudden severe dyspnea. Echocardiography shows billowing of both mitral leaflets above the annular plane into the left atrium with ruptured chordae tendineae. The characteristic histological change in his mitral valve is:

• A Fibrosis and commissural fusion of the leaflets
• B Dystrophic calcification of the annulus with sparing of leaflets
• C Myxomatous expansion of the spongiosa layer with deposition of mucopolysaccharide-rich material ✓
• D Vegetations along the line of closure with fibrin and platelets

Explanation

Mitral valve prolapse is caused by myxomatous degeneration: marked thickening of the spongiosa layer with accumulation of mucopolysaccharide-rich extracellular matrix, which weakens the fibrosa and allows leaflet billowing. It is frequent in Marfan syndrome due to fibrillin-1 mutations, and chordal rupture can cause acute severe mitral regurgitation. Commissural fusion defines rheumatic disease, annular calcification is seen in elderly patients, and sterile platelet-fibrin vegetations describe NBTE.

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.