Cell Necrosis

Question 1

What is the definition of necrosis?

Answer 1

the death of cells or groups of cells within a living organism

Question 2

Differentiate between necrosis and autolysis?

Answer 2

Necrosis is seen in the living with inflammation

autolysis is seen in tissues after death

Question 3

What are the there different types of necrosis?

Answer 3

coagulative, liquefactive, caseous and fat

Question 4

What is Coagulative Necrosis?

Answer 4

The most common form of necrosis. Occurs when cells proteins are altered or denatured.
when observed histologically the cell outline are preserved and the cytoplasm appears finely granular

coagulative necrosis in cells can be compared to the coagulation that occurs when cooking eggs

Question 5

Examples of Coagulative Necrosis

Answer 5

this type of necrosis is typically observed in solid internal organs (heart, kidney. liver, spleen) and is most often caused by anoxia resulting from ischemia

Question 6

Best example of Coagulative Necrosis

Answer 6

death of heart tissue as a result of a myocardial infarction

Question 7

what leukocyte is found microscopically during examination of coagulative necrosis

Answer 7

neutrophils

in an Acute Myocardial Infarct you may also observe dead heart muscle cells

Question 8

What is Liquefactive Necrosis?

Answer 8

process in which dead cells liquify under the influence of certain cell enzymes, resulting in soft and gel-like tissues
there will be a high concentration of neutrophils present

Question 9

Examples of Liquefactive Necrosis

Answer 9

most often Liquefactive Necrosis occurs the the brain, resulting in loss of contours and liquefaction of brain cells.
loss of blood supply to the brain (i.e. stroke) causing softening and ultimately transformation into a fluid-filled cavity, common in drowning

this necrosis can also be seen in certain bacterial infections in which a cavity may develop, such as abscesses in the lungs

Question 10

What is Caseous Necrosis?

Answer 10

a form of coagulative necrosis in which a thick yellowish and cheesy substance forms

Question 11

Example of Caseous Necrosis

Answer 11

Tuberculosis
lung granulomas are formed encasing areas of caseous necrosis
this is called the Ghon Complex and many patients will heals, and the infection in contained within the granuloma

we may also observe cases necrosis in some fungal infections such as histoplasmosis (infection by a fungus found in the droppings of birds and bats in humid areas, not serious if contained within the lung but can be problematic or fatal if spread throughout the body)

Question 12

What is Fat Necrosis?

Answer 12

A specialized form of liquefaction necrosis caused by the action of lipolytic enzymes

Question 13

Examples of Fat Necrosis

Answer 13

It is limited to fat tissue, usually around the pancreas, where enzymes are released into the adjacent fat tissue, usually after rupture of the pancreas (trauma, acute pancreatitis from excessive ETHOL consumption), causing degradation of fat into glycerol and free fatty acids. The free fatty acids rapidly bind with calcium, forming soaps, causing white, calcified specks
Breast is another common site for fat necrosis, resulting in features that mimic breast cancer findings

Question 14

Necrotic tissue and bacteria

Answer 14

Necrotic tissue can provide a good medium for infection by bacteria

Question 15

Wet gangrene

Answer 15

The bacterial infection of coagulated tissue leads to inflammation and a secondary liquefaction clinically known as wet gangrene
an example is advanced decubitus ulcers

Question 16

Dry gangrene

Answer 16

if the necrotic tissue dries out it become black and mummified

Question 17

Give underlying conditions that contribute to Gangrene?

Answer 17

Gangrene infections frequently occur after an infarction of the intestines or in a limb and are usually caused be atherosclerosis or diabetes

Question 18

What are Dystrophic Calcifications?

Answer 18

macroscopic deposition of calcium in injured or dead tissues. Represents an extracellular deposition of calcium from the circulation into dead or dying necrotic tissue, often visible to the naked eye, and range from gritty, sand-like grains to firm, rock-hard material

common in arteries

Question 19

Necrotic tissue and calcium

Answer 19

Necrotic tissue attracts calcium salts and frequently undergoes calcification

Question 20

Mammograms and Dystrophic Calcifications

Answer 20

Breast calcifications routinely appear on breast cancer screening mammograms.
Most breast calcifications are caused by benign breast changes
However calcifications and microcalcifications (that are smaller and usually found ‘earlier‘) are considered to be a breast cancer risk

Question 21

examples of Dystrophic Calcification (4)

Answer 21

1. Calcifications in Atherosclerotic coronary arteries contributes to narrowing of the vessels. Harder to get blood through these vessels, must use a balloon angioplasty
2. Calcifications of the Mitral or Aortic valves leading to impeded blood flow (Stenosis)
3. Calcifications seen around breast cancers that can be visualized by mammography.
4. Infant periventricular calcifications seen in congenital Toxoplasmosis.

Question 22

Toxoplasmosis

Answer 22

Parasitic infection, parasites can cross the placental and result in Infant periventricular calcifications
This is why we recommend pregnant women to stay away from the litter box (i.e. cleaning litter box), The parasites are commonly found ing the feces of cats and can migrate to the air and then be breathed in and cross the placental to the developing fetus

Question 23

What are Metastatic Calcifications?

Answer 23

Reflects deranged calcium metabolism (not cell injury), usually associated with increased serum calcium levels, leading to deposition of calcium in other locations

Question 24

Examples of Metastatic Calcifications

Answer 24

seen in various disorders including Hyperparathyroidism, vitamin D toxicity and Chronic Renal Failure.
causes formation of calcium stones in sites such as the gallbladder, kidneys and bladder due to precipitation of the salts from solution into tissues