A 26-year-old tall, thin woman has a mid-systolic click followed by a late systolic murmur. Echocardiography shows systolic billowing of one mitral leaflet beyond the annular plane. The characteristic histological change in the affected leaflet is:

• A Fibrous thickening of the fibrosa with commissural fusion
• B Granulomatous inflammation with giant cells
• C Dystrophic calcification of the annulus
• D Accumulation of loose proteoglycan-rich material in the spongiosa ✓

Explanation

Mitral valve prolapse is caused by myxomatous (mucoid) degeneration: expansion of the middle spongiosa layer by accumulated mucopolysaccharide-rich ground substance, which weakens the collagenous fibrosa and lets the leaflet billow. Commissural fusion with fibrosal scarring defines chronic rheumatic disease; annular calcification is seen in elderly degenerative disease; granulomas suggest rheumatic carditis.

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.