A 28-year-old woman from rural India presents with dyspnea and palpitations. Echocardiography reveals mitral stenosis with a diastolic murmur. Regarding the pathological features of rheumatic mitral stenosis, all of the following are true EXCEPT:
A. Commissural fusion of mitral leaflets is the hallmark finding
B. Macrophage infiltration and Aschoff bodies are seen in the acute phase
C. Chordae tendinae undergo shortening and thickening
D. The aortic valve is more commonly affected than the mitral valve in rheumatic heart disease
Explanation
Pathological Features of Rheumatic Heart Disease
Valve Involvement Hierarchy
Key Point
The mitral valve is the MOST commonly affected valve in rheumatic heart disease (RHD), followed by the aortic valve. The tricuspid and pulmonary valves are rarely involved.
Table
Valve
Frequency
Lesion Type
Mitral
70–80%
Stenosis > regurgitation
Aortic
20–30%
Regurgitation > stenosis
Tricuspid
5–10%
Usually secondary to RV dilatation
Pulmonary
<1%
Rare, usually secondary
Pathological Changes in Mitral Stenosis
1.
Commissural Fusion — leaflets fuse at the commissures, restricting opening; this is the hallmark of mitral stenosis.
Leaflet Changes — thickening, calcification, and fibrosis; leaflets become rigid and immobile.
4.
Aschoff Bodies — granulomatous lesions with central fibrinoid necrosis surrounded by Anitschkow cells and Aschoff giant cells; seen in acute rheumatic fever.
The progression from acute rheumatic fever to chronic RHD takes years; repeated streptococcal infections accelerate valve damage.
Warning
Do NOT confuse the sequence — acute inflammation precedes chronic fibrosis. Aschoff bodies are seen in the acute phase, NOT in chronic stenotic mitral valve.
Why Option 2 is Correct
The aortic valve is involved in only 20–30% of RHD cases and is NEVER the primary or most common valve affected. The mitral valve is affected in 70–80% of cases. This statement is FALSE and is the correct answer to an "EXCEPT" question.
Robbins 10e Ch 12
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