Liver - Necrosis







comment:
The extent, pattern, and morphologic features of hepatocellular necrosis depend on the degree of metabolic activation of hepatotoxic xenobiotics, host response to the toxicant, dose and duration of xenobiotic exposure, and timing of liver sample evaluation after dosing. Classical coagulation necrosis is typically caused by ischemia or infarction, and tissue architecture is somewhat maintained because lysosomal enzymes responsible for proteolysis are denatured. Another form of necrosis, liquefaction necrosis, may result in cellular dissolution and loss of cytologic architecture. Changes that may accompany necrosis include hemorrhage, fatty change, cytoplasmic vacuolization, cytologic degeneration, and inflammatory cell infiltration.Figure 1









Figure 9


recommendation:
Necrosis should not be subclassified based on type, with the exception of single-cell necrosis. For a given xenobiotic, dose and animal variability in response can influence whether hepatocellular necrosis is panlobular or centrilobular and whether it is focal or occurs in extensive irregular patches. If the fundamental process is the same, the lesion(s) should be recorded simply as necrosis and assigned a severity grade. The pattern and other features of the hepatocellular necrosis should be described in the pathology narrative. Splitting out diagnoses too finely will result in complicated incidence tables and may compromise appropriate interpretation of any induced toxicity. When accompanying changes such as fatty change or inflammation are sufficiently extensive, separate diagnoses may be warranted with severity grading and discussion in the pathology narrative. Since degeneration is considered part of the continuum of changes involved in the necrotic process, it should not be diagnosed separately when present with necrosis. However, degeneration without necrosis may occur at exposure levels below doses that cause necrosis and thus may warrant a separate diagnosis. In some cases, hepatocellular necrosis can result in cavernous, blood-filled spaces within the hepatic parenchyma. These blood-filled spaces should not be diagnosed as hemorrhage because they are secondary to necrosis.references:
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Web page last updated on: January 13, 2014