Necrosis Types in Pathology

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Questions and Answers

What is the primary characteristic of liquefactive necrosis?

Replacement of tissue with basophilic materials

Replacement of tissue by structureless materials (correct)

Preservation of tissue architecture

Formation of well-defined fibrous capsules

In liquefactive necrosis, what primarily causes the necrotic area to appear opaque and chalky?

Release of proteolytic enzymes (correct)

Necrosis of adipose tissue

Dense fibrous tissue formation

Accumulation of neutrophils

Which of the following composite cell types are typically involved in liquefactive necrosis?

Erythrocytes and platelets

Lymphocytes and fibroblasts

Neutrophils and macrophages (correct)

Basophils and mast cells

What kind of bacteria are typically associated with liquefactive necrosis that leads to pus formation?

Virulent pathogenic bacteria Signup and view all the answers

What happens to the necrotic area in liquefactive necrosis when it is invaded by pyogenic bacteria?

Formation of pus and further inflammatory response Signup and view all the answers

Which factor is NOT associated with the pathogenesis of liquefactive necrosis?

Formation of crystalline soap deposits Signup and view all the answers

What potential consequence may occur if necrotic tissue undergoes further bacterial invasion?

It may result in gangrene Signup and view all the answers

Which of the following is a typical sequence of events in liquefactive necrosis?

Absorption of necrotic material by lymphatics Signup and view all the answers

Which characteristic is most representative of liquefactive necrosis?

Formation of a gelatinous mass Signup and view all the answers

What is a common cause of liquefactive necrosis?

Bacterial infections Signup and view all the answers

Which of the following statements about liquefactive necrosis is false?

The tissue is replaced by a solid mass. Signup and view all the answers

Liquefactive necrosis primarily results in what type of cellular change?

Loss of cell outline Signup and view all the answers

What primarily characterizes liquefactive necrosis?

Formation of soft, fluid-filled cavities Signup and view all the answers

In which tissue type is liquefactive necrosis most commonly observed?

Nervous tissue Signup and view all the answers

In which organ is liquefactive necrosis most commonly observed?

Brain Signup and view all the answers

What gross characteristic is typically seen in liquefactive necrosis?

Soft and mushy consistency Signup and view all the answers

Which of the following is a cause of liquefactive necrosis?

Pathogenic bacterial infections Signup and view all the answers

What microscopic change occurs in liquefactive necrosis?

Dissolution of tissues into a viscous substance Signup and view all the answers

What microscopic feature is typical of liquefactive necrosis?

Pinkish or empty cavities Signup and view all the answers

Which type of necrosis is characterized by the presence of dead tissue with a liquefied appearance?

Liquefactive necrosis Signup and view all the answers

Which process can lead to the liquefactive necrosis of nervous tissue?

Death of neutrophils releasing enzymes Signup and view all the answers

What is the gross appearance of tissue affected by liquefactive necrosis?

Cyst-like cavities filled with fluid Signup and view all the answers

Which of the following statements about liquefactive necrosis is NOT true?

It typically involves the coagulation of striated muscles. Signup and view all the answers

How does the inflammatory process contribute to liquefactive necrosis?

By activating lytic enzymes that digest dead tissue Signup and view all the answers

Study Notes

Zenker’s Necrosis

Characterized by coagulative necrosis of striated muscles where the protein of the sarcoplasm coagulates.
Etiology: Vitamin E deficiency, toxins of pathogenic microorganisms like Clostridia, ischemia, viral infection
Macroscopic Picture: Affected muscles appear as white, gray or yellow foci and streaks parallel with the muscle fibers
Microscopic Picture: Affected muscle fibers appear swollen, homogenous and eosinophilic. Loss of both longitudinal and cross striations in longitudinal sections. The cross section doesn’t show the fields of Cohenheim. Nuclei of muscle fibers are pyknotic. Muscle showing coagulative necrosis (Zenker's necrosis) infiltrated with inflammatory cells

Caseous Necrosis

Characterized by disappearance of both tissue architecture and cellular details. Tissue is replaced by granular cheesy like material or granular eosinophilic and basophilic debris.
Seen in: Tuberculosis, and other granulomas
Causes: Granuloma as T.B., Antigen-antibody reaction (allergic necrosis).
Macroscopic Presentation: The area of necrosis is soft, granular, and friable with a cream-cheesy appearance.
Microscopic Presentation: Lymph node infected with tuberculosis showing caseous necrosis characterized by replacement of the lymphoid tissue with eosinophilic and basophilic debris.

Liquefactive Necrosis

Characterized by disappearance of both tissue architecture and cellular details with replacement of the necrotic tissue with fluid.
Tissue Affected: Central nervous system: the nervous tissue is rich in non-coagulable lipoidal substances and poor in coagulable albumin.
In Suppurative Inflammation: Numerous neutrophils die and liberate proteolytic enzymes. These enzymes in addition to the lytic toxins (lysin) produced by the pathogenic bacteria digest the dead tissue into fluid.
Macroscopic Picture: Cyst like cavities of variable size in nervous tissue with or without fluid.
Microscopic Picture: Pinkish or empty cavities are seen in the nervous tissue. Evidence of necrosis is seen in the cell lining the cavities. Pus (intact and fragmented neutrophils, with necrotic cellular debris and fibrin) in suppurative inflammation. Inflammatory reaction (vascular and exudative) surrounds the necrotic areas.

Fat Necrosis

Death of the adipose tissue.
Characterized by: Disappearance of both tissue architecture and cellular details and the tissue is replaced by soap.
Types: Internal or abdominal or pancreatic fat necrosis, External or subcutaneous or traumatic fat necrosis.
Causes of Internal Fat Necrosis: Acute pancreatitis, neoplasms of pancreas
Pathogenesis of Internal Fat Necrosis: The enzyme lipase which escapes from the ruptured pancreatic duct act on the fat of the omentum, mesentery and abdominal organs. Lipase split fat into glycerol and fatty acid. Glycerol is absorbed in the blood. Fatty acids combine with sodium, potassium, or calcium to form soap.
Causes of External Fat Necrosis: Trauma in the adipose tissue of the breast and subcutaneous fat. The fat cell rupture and self digestion takes place.
Macroscopic Picture: The necrotic area appear small dull opaque chalky white or yellowish-white and well circumscribed.
Microscopic Picture: The affected fat cells appear cloudy. It contain acicular crystal which stain blue (sodium soap), pinkish (potassium soap) or purple (calcium soap). Fat cells have pyknotic nuclei. The necrotic area is surrounded by inflammatory reaction and contains foreign body, giant cells and macrophage.

Sequelae of Necrosis

Removed by macrophage.
Liquefied and absorbed by lymphatics or veins.
Desquamation and sloughing especially in skin and mucous membrane.
Healing by regeneration or granulation tissue formation followed by fibrosis.
Invasion of the necrotic area by pyogenic bacteria with formation of pus.
Get surrounded by fibrous capsule and may show dystrophic calcification later on.
Gangrene occurred when invasion of the necrotic tissue by saprophytic bacteria.
Fatal: necrosis of the vital organs as brain, heart.

Necrosis Definition

Local death of cells inside the living body.

Cellular Characteristics of Necrosis

Nuclear Changes:
- Pyknosis: condensation of nuclear chromatin into a dark, round homogenous mass smaller than in a normal nucleus.
- Karyorrhexis: splitting of the nucleus into numerous pieces.
- Karyolysis: dissolution of nuclear chromatin, leaving a hallow, large, round, ghost form of the nucleus.
Cytoplasmic Changes:
- Increased acidophilia (most common).
- Lysis of the cytoplasm, giving a pale vacuolated appearance.
Changes in the Cell as a Whole:
- The cells as a whole loses its outline.
- Reduced differential staining of nucleus and cytoplasm.
- Complete loss of cells.

Gross Characteristics of Necrosis

Loss of color or paleness of the tissue.
Loss of strength of the tissue (softness).
Defined zone of demarcation between necrotic and viable tissue.

Types of Necrosis

Coagulative Necrosis
Caseous Necrosis
Liquefactive Necrosis
Fat Necrosis
Fibrinoid Necrosis

Coagulative Necrosis

Characterized by a maintained organ architecture and loss of cellular details.
Occurs in tissues rich with proteins such as the parenchymatous organs, skeletal muscles.
Causes: Viral infection, toxins, or lack of blood supply (ischemia).
Macroscopic Picture: The necrosed area is dry, firm and pale (grayish white or yellow).
Microscopic Picture: Organ architecture is maintained and cellular details are lost. The cytoplasm appears highly eosinophilic, granular or homogenous, structurless mass. Pyknosis and karyolysis are present in the center of the necrotic area and karyorrhexis at the borders.

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Description

This quiz explores two distinct types of necrosis: Zenker’s necrosis and caseous necrosis. It covers their characteristics, etiology, and macroscopic and microscopic appearances. Perfect for students of pathology seeking to deepen their understanding of tissue necrosis.