Necrosis

Question 1

What are the 3 types of nuclear changes during necrosis?

Answer 1

• karyolysis (nuclear membrane dissolves); nucleus becomes dark basophilic
• karypiknosis (nucleus condenses/clumps up)
• karyorrhexis (nucleus fragments and spreads out into cytoplasm)

Question 2

How does infarction in different organs appear macroscopically?

Answer 2

Heart - yellow/white zone with red rim
Lungs - 
Brain - white/grey??
Kidneys - ?
Spleen - ?

Question 3

What types of necrosis are there?

Answer 3

Coagulative
Colliquative/liquefactive 
Caseous
Gangrene
Fibrinoid *
Infarction *
Fat necrosis *

Question 4

What is the difference between thrombosis and embolism?

Question 5

What is the pathogenesis of infarction?

Answer 5

1. obstruction of blood vessel (artery, arteriole, venule, vein)
2. Lack of blood supply = hypoxia
3. Reversible cell injury (hydropic changes - build up of water in organelles = swelling)
4. Irreversible cell injury (necrosis)

Question 6

How can histopathologists classify infarcts?

Answer 6

Infarcts can be classified further by the following parameters:

• Age (is it old? is it new?)
• Colour (is it white/pale? red/hemorrhagic)
• Infection (is the infarct infected (septic)? Is the infarct not infected (bland)

Question 7

What is Waxy/Zenker’s necrosis?

Answer 7

• Necrosis of skeletal muscles, commonly in abdominal wall and internal thigh due to infectious diseases ie. typhoid fever.
• type of coagulative necrosis
• Necrosis sites resemble a wax candle

Question 8

What is the difference between coagulative and colliquative necrosis?

Answer 8

• Coagulative (dry) necrosis does not involve lytic enzymes vs colliquative (wet) necrosis

Question 9

What is hematoidin?

Answer 9

• Orange pigment
• does not contain Fe
• present due to anaerobic destruction of RBCs + Hb
• doesn’t stay in cells like hemosiderin

Question 10

What are the types of jaundice you know?

Answer 10

• hemolytic jaundice (destruction of RBCs)= deposition of hemosiderin granules; RBCs destruction may be caused by sickle cell anemia, infection, congenital blood defect. The liver is overwhelmed with so much bilirubin, that it can’t break it down = build up of unconjugated bilirubin
• obstructive jaundice/post-hepatic jaundice - liver has successfully conjugated bilirubin but it can;t get into intestine. Since this conjugated bilirubin is water soluble it enters kidenys and comes out in urine instead = green urine
• intrahepatic jaundice - liver cells can’t combine with bilirubin to remove it + it can’t leave liver and go to intestine; unconjugated and conjugated bilirubin increase in system

Question 11

In hemolytic jaundice, there is an accumulation of unconjugated bilirubin. Unconjugated bilirubin is less soluble than conjugated bilirubin - what is the consequence of this?

Answer 11

• the unconjugated bilirubin supersaturates the plasma and may crystallise in the tissues and brain causing necrosis = kernicterus (bilirubin encephalopathy)