Cell Death: Necrosis Charles L. Hitchcock, MD, PhD Department of Pathology Wexner Medical Center at The Ohio State University

Primary Learning Objective Integrate cellular physiology with the type and duration of cell injury to predict the morphology and mechanisms of cellular response to injury.

Secondary Learning Objectives Describe the morphologic features of a necrotic cell. Identify coagulative necrosis from an image or description and correlate with the possible etiology and mechanisms of cell death. Identify liquefactive necrosis from an image or description and correlate with the possible etiology and mechanisms of cell death.

Secondary Learning Objectives Identify caseating necrosis from an image or description and correlate with the possible etiology and mechanisms of cell death. Identify fat necrosis from an image or description and correlate with the possible etiology and mechanisms of cell death.

Necrosis Necrosis is a morphologic expression of cell death resulting from different patterns of lysosomal enzyme degradation of cells and extracellular matrix, the type of necrotic debris, and by bacterial products when present.

Etiologies Of Necrosis Ischemic injury Cancer Chemical injury –Unaltered chemicals may directly injure cells (e.g. Hg, CN) –Metabolites of P-450 mixed function oxidases metabolism may result in toxic intermediates or metabolites (e.g. CCl4 or acetaminophen) that damage cells Infections such a tuberculosis.

Membrane Changes in Necrosis

MYOCARDIAL INFARCT Normal Necrotic NormalNecroticHydropic change

Nuclear Changes in Necrosis Normal Pyknosis Karyorrhexis Karyolysis Normal Pyknosis Karyorrhexis Karyolysis Karyolysis Pyknosis Karyorrhexis

Cytoplasmic Changes in Necrosis

Normal Myocardium Necrotic Myocardium

Morphologic Types of Necrosis Coagulative Necrosis Liquefactive Necrosis Caseous Necrosis Fat Necrosis Morphologic Types of Necrosis

Coagulative Necrosis Normal Myocardium Necrotic Myocardium

Coagulative Necrosis Recent infarct

Coagulative Necrosis

Liquefactive Necrosis Abscess

Caseous Necrosis Lung TB

Fat Necrosis Omentum in pancreatitis

Sequela of Necrosis Scarring and loss of organ function Inflammation Formation of ulcers and cavitary lesions Calcification Resolution Autoimmune response due to tissue destruction release of self-antigen.

Summary Morphologic features of necrosis help to define the underlying cause. –Cellular pattern of death –Type of cell debris –Type of inflammation

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