Lipofuscin

1. 2.  
      Lipofuscin
       
      1.  
         This yellowish, fat-soluble pigment is an end product of membrane lipid peroxidation.
      2.  
         It is sometimes referred to as “wear-and-tear” pigment.
      3.  
         It commonly accumulates in elderly patients, in whom the pigment is found most often within hepatocytes and at the poles of nuclei of myocardial cells. The combination of lipofuscin accumulation and atrophy of organs is referred to as brown atrophy.
2.  
   Pathologic calcifications
    
   1.  
      Metastatic calcification
       
      1.  
         The cause of metastatic calcification is hypercalcemia.
      2.  
         Hypercalcemia most often results from any of the following causes:
          
         1.  
            Hyperparathyroidism
         2.  
            Osteolytic tumors with resultant mobilization of calcium and phosphorus
         3.  
            Hypervitaminosis D
         4.  
            Excess calcium intake, such as in the milk-alkali syndrome (nephrocalcinosis and renal stones caused by milk and antacid self-therapy)
   2.  
      Dystrophic calcification
       
      1.  
         Dystrophic calcification is defined as calcification in previously damaged tissue, such as areas of old trauma, tuberculosis lesions, scarred heart valves, and atherosclerotic lesions (Figure 1.7).
          

         FIGURE 1.7

         

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         Calcific aortic stenosis.

         This is an example of dystrophic calcification, that is, calcification of a previously damaged structure.

         (Reprinted with permission from Rubin R, Strayer D et al., eds.: Rubin’s Pathology. Clinicopathologic Foundations of Medicine, 6th ed. Baltimore, Lippincott Williams & Wilkins, 2012, Figure 1-10, p. 13.)
      2.  
         The cause is not hypercalcemia; typically, the serum calcium concentration is normal.

Cellular Response to Physiologic and Pathologic Conditions

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