4/19/10

PATHOLOGIC CALCIFICATIONS

Pathologic calcification involves the abnormal tissue depo­sition of calcium salts, together with smaller amounts of iron, magnesium, and other minerals. It is known as dys-trophic calcification when it occurs in dead or dying tissue and as metastatic calcification when it occurs in normal tissue.

Dystrophic Calcification

Dystrophic calcification represents the macroscopic depo­sition of calcium salts in injured tissue. It is often visible to the naked eye as deposits that range from gritty sandlike grains to firm, hard, rock material. The pathogenesis of dystrophic calcification involves the intracellular or extra­cellular formation of crystalline calcium phosphate. The components of the calcium deposits are derived from the bodies of dead or dying cells as well as from the circulation and interstitial fluid.

Dystrophic calcification is commonly seen in athero-matous lesions of advanced atherosclerosis, areas of injury in the aorta and large blood vessels, and damaged heart valves. Although the presence of calcification may only indicate the presence of previous cell injury, as in healed tu­berculosis lesions, it is also a frequent cause of organ dys­function. For example, calcification of the aortic valve is a frequent cause of aortic stenosis in elderly people

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