At autopsy of a patient with long-standing rheumatic heart disease, an irregular map-like area of endocardial thickening is found on the posterior wall of the left atrium above the mitral valve. This lesion results from:

• A Organized mural thrombus overlying old infarction
• B Chronic pressure overload from systemic hypertension
• C Direct extension of Aschoff inflammation from the valve
• D Regurgitant jet of blood damaging the endocardium ✓

Explanation

The MacCallum patch is an area of endocardial fibrous thickening on the posterior left atrial wall above the posterior mitral leaflet. It is caused by trauma from the regurgitant jet of blood striking that endocardial surface in mitral regurgitation, followed by organization and fibrosis. It is not composed of Aschoff bodies, does not represent an organized thrombus, and hypertension produces concentric left ventricular hypertrophy rather than focal atrial endocardial scarring.

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.