Histological examination of an excised mitral valve from a 30-year-old woman with a mid-systolic click shows expansion of the spongiosa layer by loose, acellular myxomatous connective tissue, thinning of the fibrosa, and attenuation of the valve surface endothelium. What is the diagnosis?
- A Rheumatic mitral valve disease
- B Myxomatous degeneration (mitral valve prolapse) ✓
- C Mitral annular calcification
- D Libman-Sacks endocarditis
Explanation
The hallmark of myxomatous degeneration is deposition of excess glycosaminoglycan-rich matrix within the spongiosa, weakening the leaflets so they billow or prolapse during systole, producing the classic mid-systolic click. Chordae tendineae may elongate and occasionally rupture. Rheumatic disease instead shows diffuse fibrous thickening with commissural fusion and neovascularization, while Libman-Sacks vegetations are superficial fibrin deposits. Annular calcification is a degenerative change of older patients involving the annulus itself, not myxoid expansion of the leaflet layers.
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.