Necrosis

Question 1

What type of necrosis occurs in tissues (except brain) which become ischemic (due to infarcts)

Answer 1

Coagulative necrosis

Question 2

What does coagulative necrosis look like on histology?

Answer 2

• Nuclei disappear
• Preserved cellular archicecture (cell outlines seen)
• Increased cytoplasmic binding of eosin atain (increased eosinophilia: red/pink colour)

Question 3

When does liquefactive necrosis occur?

Answer 3

• Brain infarct
• Bacterial abscesses
• Pancreatitis

Question 4

Why in coagulative necrosis is cell architecture preserved?

Answer 4

Proteolysis and lysosomal enzymes are denatured

Question 5

What is liquefactive necrosis due to?

• What cells are responsible?
• What do they release?

Answer 5

Neutropils releasing lysosomal enzymes that digest tissue

Question 6

Describe the histology of liquefactive necrosis in the brain

Answer 6

• Early: cellular debris and macrophages seen

- Late: Cystic spaces and cavitation

Question 7

What cells and things can be seen on histology in liquefactive necrosis due to bacterial infection?

Answer 7

Neutrophils and cell debris seen

Question 8

What can cause caseous necrosis?

Answer 8

• TB
  Fungi
• e.g Histoplasma capsulatum (HIV)
• Nocardia

Question 9

Desribe caseous necrosis

Describe what a granuloma is

Answer 9

Macrophages wall off the infecting microorganisms - creates granular debris

• Fragmented cells and debris surrounded by lymphocytes and macrophages (granuloma)

Question 10

What can cause fat necrosis?

How can the 2 types be divided?

Answer 10

Pancreatitis - enzymatic type

Traumatic (breast necrosis) - nonenzymatic

Question 11

How does pancreatitis cause fat necrosis?

Answer 11

Damaged pancreatic cells release lipase

Question 12

What is pyknosis?

Answer 12

Shrinkage of the nucleus

Question 13

What is karyorrhexis?

Answer 13

Nucleus breaking into pieces

Question 14

What is karyolysis?

Answer 14

Nucleus being broken down into basic building blocks

Question 15

What are the 3 mechanisms by which cell death (or the loss of the nucleus) occurs?

Answer 15

• Pyknosis
• Karyorrhexis
• Karyolysis

Question 16

What colour are nuclei?

Answer 16

Dark blue

Question 17

When may a red infarction occur?

Answer 17

If blood re-enters a loosely organised tissue

Question 18

What is gangrenous necrosis?

Answer 18

Coagulative necrosis

- Resembles mummified tissue

Question 19

What is wet gangrene?

Answer 19

Superimposed infection of coagulative (dry) necrosis

• Pus creates wetness
• Liquefactive necrosis

Question 20

What will be seen on histology in fibrinoid necrosis?

Answer 20

Vessel walls contain eosinophilic layer of proteinaceous material

Question 21

What is fibrinoid necrosis due to (2 mechanisms)?

Answer 21

• Immune complex deposition (T3 HS reaction)

- And/or plasma protein (fibrin) leakage from damaged vessel

Question 22

Give 2 MOA of fibrinoid necrosis?

Answer 22

• Immune vascular reactions (eg PAN)

- Nonimmune vascular reactions (eg HS emergency preeclampsia)

Question 23

What is saponification?

Answer 23

Fatty acids released by trauma or lipase join with calcium

- E.g dystrophic calcification

Question 24

How can dystrophic and metastatic calcification be differentiated by blood tests?

Answer 24

In metastatic the serum calcium and/or phosphate will be raised

Question 25

What will leaking of proteins into vessel wall look like in staining?

Answer 25

Bright pink staining

Question 26

What type of necrosis occurs due to malignant hypertension

Answer 26

Fibrinoid necrosis

Question 27

Fibrinoid necrosis of the placental blood vessels occurs due to what?

Answer 27

Pre-eclampsia