Necrosis Flashcards

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1
Q

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

A

Coagulative necrosis

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2
Q

What does coagulative necrosis look like on histology?

A
  • Nuclei disappear
  • Preserved cellular archicecture (cell outlines seen)
  • Increased cytoplasmic binding of eosin atain (increased eosinophilia: red/pink colour)
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3
Q

When does liquefactive necrosis occur?

A
  • Brain infarct
  • Bacterial abscesses
  • Pancreatitis
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4
Q

Why in coagulative necrosis is cell architecture preserved?

A

Proteolysis and lysosomal enzymes are denatured

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5
Q

What is liquefactive necrosis due to?

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

Neutropils releasing lysosomal enzymes that digest tissue

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6
Q

Describe the histology of liquefactive necrosis in the brain

A
  • Early: cellular debris and macrophages seen

- Late: Cystic spaces and cavitation

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7
Q

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

A

Neutrophils and cell debris seen

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8
Q

What can cause caseous necrosis?

A
  • TB
    Fungi
  • e.g Histoplasma capsulatum (HIV)
  • Nocardia
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9
Q

Desribe caseous necrosis

Describe what a granuloma is

A

Macrophages wall off the infecting microorganisms - creates granular debris

  • Fragmented cells and debris surrounded by lymphocytes and macrophages (granuloma)
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10
Q

What can cause fat necrosis?

How can the 2 types be divided?

A

Pancreatitis - enzymatic type

Traumatic (breast necrosis) - nonenzymatic

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11
Q

How does pancreatitis cause fat necrosis?

A

Damaged pancreatic cells release lipase

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12
Q

What is pyknosis?

A

Shrinkage of the nucleus

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13
Q

What is karyorrhexis?

A

Nucleus breaking into pieces

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14
Q

What is karyolysis?

A

Nucleus being broken down into basic building blocks

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15
Q

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

A
  • Pyknosis
  • Karyorrhexis
  • Karyolysis
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16
Q

What colour are nuclei?

A

Dark blue

17
Q

When may a red infarction occur?

A

If blood re-enters a loosely organised tissue

18
Q

What is gangrenous necrosis?

A

Coagulative necrosis

- Resembles mummified tissue

19
Q

What is wet gangrene?

A

Superimposed infection of coagulative (dry) necrosis

  • Pus creates wetness
  • Liquefactive necrosis
20
Q

What will be seen on histology in fibrinoid necrosis?

A

Vessel walls contain eosinophilic layer of proteinaceous material

21
Q

What is fibrinoid necrosis due to (2 mechanisms)?

A
  • Immune complex deposition (T3 HS reaction)

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

22
Q

Give 2 MOA of fibrinoid necrosis?

A
  • Immune vascular reactions (eg PAN)

- Nonimmune vascular reactions (eg HS emergency preeclampsia)

23
Q

What is saponification?

A

Fatty acids released by trauma or lipase join with calcium

- E.g dystrophic calcification

24
Q

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

A

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

25
Q

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

A

Bright pink staining

26
Q

What type of necrosis occurs due to malignant hypertension

A

Fibrinoid necrosis

27
Q

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

A

Pre-eclampsia