What are the microscopic changes during necrosis?
The necrotic tissue appears as white and friable, like clumped cheese. Dead cells disintegrate but are not completely digested, leaving granular particles. Microscopic examination shows amorphous granular debris enclosed within a distinctive inflammatory border. Some granulomas contain this pattern of necrosis.
What are the microscopic appearances of a dead tissue?
When cells die by necrosis, they exhibit two major types of microscopes or macroscopic appearance. The first is liquefactive necrosis, also known as colliquative necrosis, is characterized by partial or complete dissolution of dead tissue and transformation into a liquid, viscous mass.
What does liquefactive necrosis look like?
In liquefactive necrosis, the affected cell is completely digested by hydrolytic enzymes, resulting in a soft, circumscribed lesion consisting of pus and the fluid remains of necrotic tissue. Dead leukocytes will remain as a creamy yellow pus.
How do you know if you have caseous necrosis?
Appearance. In caseous necrosis no histological architecture is preserved. On microscopic examination with H&E staining, it is characterized by acellular pink areas of necrosis surrounded by a granulomatous inflammatory process.
When does liquefactive necrosis occur?
Liquefactive necrosis is a type of necrosis in which the dead tissue turns into a liquid substance. This condition usually occurs in the central nervous system, especially in the brain. When the cells die, they are digested by lysosomes in the body. This digestion process results in the formation of pus-filled cysts.
Why coagulative necrosis does not occur in brain?
The lack of lysosomal enzymes allows it to maintain a “coagulated” morphology for some time. Like most types of necrosis, if enough viable cells are present around the affected area, regeneration will usually occur. Coagulative necrosis occurs in most bodily organs, excluding the brain.
Why is caseous necrosis termed caseous?
The term caseous is derived from the grass appearance of the area of necrosis, i.e. white and cheesy appearance. Caseous necrosis is encountered most often in tuberculous infection.
Where does liquefactive necrosis occur?
Liquefactive necrosis usually occurs in the brain and results in a pus-filled cyst forming. Liquefactive necrosis most often occurs in the brain because the brain has a very high concentration of lysosomes.
What is the most common cause of liquefactive necrosis?
In organs or tissues outside the CNS, liquefactive necrosis is most commonly encountered as part of pyogenic (pus-forming) bacterial infection with suppurative (neutrophil-rich) inflammation (see also Chapter 3) and is observed at the centers of abscesses or other collections of neutrophils.
How does coagulative necrosis occur?
Coagulative necrosis is most commonly caused by conditions that do not involve severe trauma, toxins or an acute or chronic immune response. The lack of oxygen (hypoxia) causes cell death in a localized area which is perfused by blood vessels failing to deliver primarily oxygen, but also other important nutrients.
What is a caseous necrosis?
The caseous necrosis is the basic process of tuberculosis disease in humans. The interval from infection to tuberculin conversion is never more than 8 weeks and in general is 5 to 7 weeks (21). The onset of caseous necrosis coincides with the development of acquired immune resistance or CMI and DTH.
What is the difference between liquefactive necrosis and coagulative necrosis?
The loss of tissue and cellular profile occurs within hours in liquefactive necrosis. In contrast to liquefactive necrosis, coagulative necrosis, the other major pattern, is characterized by the maintenance of normal architecture of necrotic tissue for several days after cell death.
What is liquefactive necrosis of the brain?
Liquefactive Necrosis. In liquefactive necrosis, cells are lysed, and the necrotic tissue is converted to a fluid phase. This manifestation is typically the final stage of necrosis in parenchyma of the brain (Fig.
What are the patterns of necrosis?
Patterns of necrosis (liquefactive or coagulative) are determined by the cause of cell death, organ affected, and duration of cell death. Liquefactive necrosis is a pattern of cell death caused by several etiological factors. The major causes of liquefactive necrosis are:
Where is liquefactive necrosis most commonly found?
In organs or tissues outside the CNS, liquefactive necrosis is most commonly encountered as part of pyogenic (pus-forming) bacterial infection with suppurative (neutrophil-rich) inflammation (see also Chapter 3) and is observed at the centers of abscesses or other collections of neutrophils.