Histological examination of a mitral valve resected from a 28-year-old man with severe mitral valve prolapse shows expansion of the middle spongiosa layer of the leaflet. What material accounts for this expansion?

• A Collagen deposited by activated fibroblasts
• B Fibrin and platelets from repeated microthrombi
• C Amyloid composed of serum amyloid A protein
• D Accumulated acid mucopolysaccharide (proteoglycan) matrix ✓

Explanation

Myxomatous degeneration of the mitral valve, the substrate of Barlow syndrome and mitral valve prolapse, is characterised by expansion of the spongiosa layer with accumulated acid mucopolysaccharides (proteoglycans), producing redundant, thickened, gelatinous leaflets with elongated chordae prone to rupture. The fibrosa layer is thinned rather than collagen rich, distinguishing this from post-inflammatory scarring and from amyloidosis.

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.