MEDizzy - At autopsy, the heart of a 63-year-old man weighs only 250 g

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Cellular Pathology

At autopsy, the heart of a 63-year-old man weighs only 250 g (normal 330 g) and has small right and left ventricles. The myocardium is firm, with a dark chocolate-brown color throughout. The coronary arteries show minimal atherosclerotic changes. An excessive amount of which of the following substances would most likely be found in the myocardial fibers of this heart?

ExplanationLipofuscin is a “wear-and-tear” pigment that increases with aging, particularly in the liver and myocardium. This granular golden brown pigment has minimal effect on cellular function in most cases. Rarely, there is marked lipofuscin deposition in a small heart, a so called brown atrophy. Bilirubin, another breakdown product of hemoglobin, imparts a yellow appearance (icterus) to tissues. Hemosiderin is the breakdown product of hemoglobin that contains iron. Hearts with excessive iron deposition tend to be large. Glycogen is increased in some inherited enzyme disorders, and when the heart is involved, heart size increases.