Notes on Necrosis from Visual Pathology Lab Lecture

Introduction to Necrosis

• Definition: Necrosis is the result of proteolytic digestion of the cell and its contents.
• Causes:
  • Release of enzymes such as proteases and endonucleases due to cell injury.
  • Continuous cell injury leads to cell death.

Morphology of Necrosis

• Different categories of necrosis exist based on the type of organ affected.
• Visual aids, such as images, will be used to illustrate these types.

Types of Necrosis

1. Coagulative Necrosis

• Characteristics:
  • Occurs in solid organs that are not soft or rubbery.
  • Enzymatic leakage leads to cell injury and necrosis.
• Mechanism:
  • Leakage of proteolytic enzymes and rupture of cell membranes.
  • Architecture of the cell remains, but internal content is affected.
• Examples:
  • Spleen: White areas represent coagulative necrosis.
  • Kidney: Yellowish necrotic area shows infection.
• Microscopic Features:
  • Loss of cellular contact.
  • Eosinophilia (pinkish coloration of cytoplasm).
  • Nuclear changes: fading of nuclei, shrinkage (pyknosis), and dark color.
  • Comparison with normal tubules shows necrotic patches.

2. Ballooning Degeneration in the Liver

• Characteristics:
  • Cells become enlarged with eosinophilic cytoplasm and faded nuclei.
• Comparison:
  • Normal hepatocyte vs. ballooned hepatocyte, showing larger size and degeneration.
  • Accumulation of bile pigments.

3. Myocardial Necrosis

• Characteristics:
  • Typical example of coagulative necrosis.
• Microscopic Features:
  • Striated fibers in normal myocardium vs. necrotic myocardium.
  • Eosinophilic cytoplasm and fading nuclei.
  • In severe cases, the tissue may appear dirty due to cytoplasmic degradation.
• Comparison:
  • Tissue architecture becomes difficult to recognize; only tiny pyknotic nuclei may remain.

Conclusion

• Coagulative necrosis is a significant pathological process in various organs.
• Further types of necrosis will be discussed in subsequent videos.