McCallum patches/plaques are usually seen in which chamber of the hea?
During acute RF, diffuse inflammation and Aschoff bodies may be found in any of the three layers of the hea, resulting in pericarditis, myocarditis, or endocarditis (pancarditis). Inflammation of the endocardium and the left-sided valves typically results in fibrinoid necrosis within the cusps or tendinous cords. Overlying these necrotic foci and along the lines of closure are small (1 to 2 mm) vegetations, called verrucae. Thus, RHD is one of the forms of vegetative valve disease, each of which exhibit their own characteristic morphologic features. Subendocardial lesions, perhaps exacerbated by regurgitant jets (Mitral regurgation), can induce irregular thickenings called MacCallum plaques, usually in the left atrium. The cardinal anatomic changes of the mitral valve in chronic RHD are leaflet thickening, commissural fusion and shoening, and thickening and fusion of the tendinous cords. In chronic disease the mitral valve is viually always involved. The mitral valve is affected in isolation in roughly two thirds of RHD, and along with the aoic valve in another 25% of cases.
Left atrium
Right atrium
Left ventricle
Right ventricle
NEET 2019