Necrosis Flashcards
What type of necrosis occurs in tissues (except brain) which become ischemic (due to infarcts)
Coagulative necrosis
What does coagulative necrosis look like on histology?
- Nuclei disappear
- Preserved cellular archicecture (cell outlines seen)
- Increased cytoplasmic binding of eosin atain (increased eosinophilia: red/pink colour)
When does liquefactive necrosis occur?
- Brain infarct
- Bacterial abscesses
- Pancreatitis
Why in coagulative necrosis is cell architecture preserved?
Proteolysis and lysosomal enzymes are denatured
What is liquefactive necrosis due to?
- What cells are responsible?
- What do they release?
Neutropils releasing lysosomal enzymes that digest tissue
Describe the histology of liquefactive necrosis in the brain
- Early: cellular debris and macrophages seen
- Late: Cystic spaces and cavitation
What cells and things can be seen on histology in liquefactive necrosis due to bacterial infection?
Neutrophils and cell debris seen
What can cause caseous necrosis?
- TB
Fungi - e.g Histoplasma capsulatum (HIV)
- Nocardia
Desribe caseous necrosis
Describe what a granuloma is
Macrophages wall off the infecting microorganisms - creates granular debris
- Fragmented cells and debris surrounded by lymphocytes and macrophages (granuloma)
What can cause fat necrosis?
How can the 2 types be divided?
Pancreatitis - enzymatic type
Traumatic (breast necrosis) - nonenzymatic
How does pancreatitis cause fat necrosis?
Damaged pancreatic cells release lipase
What is pyknosis?
Shrinkage of the nucleus
What is karyorrhexis?
Nucleus breaking into pieces
What is karyolysis?
Nucleus being broken down into basic building blocks
What are the 3 mechanisms by which cell death (or the loss of the nucleus) occurs?
- Pyknosis
- Karyorrhexis
- Karyolysis
What colour are nuclei?
Dark blue
When may a red infarction occur?
If blood re-enters a loosely organised tissue
What is gangrenous necrosis?
Coagulative necrosis
- Resembles mummified tissue
What is wet gangrene?
Superimposed infection of coagulative (dry) necrosis
- Pus creates wetness
- Liquefactive necrosis
What will be seen on histology in fibrinoid necrosis?
Vessel walls contain eosinophilic layer of proteinaceous material
What is fibrinoid necrosis due to (2 mechanisms)?
- Immune complex deposition (T3 HS reaction)
- And/or plasma protein (fibrin) leakage from damaged vessel
Give 2 MOA of fibrinoid necrosis?
- Immune vascular reactions (eg PAN)
- Nonimmune vascular reactions (eg HS emergency preeclampsia)
What is saponification?
Fatty acids released by trauma or lipase join with calcium
- E.g dystrophic calcification
How can dystrophic and metastatic calcification be differentiated by blood tests?
In metastatic the serum calcium and/or phosphate will be raised
What will leaking of proteins into vessel wall look like in staining?
Bright pink staining
What type of necrosis occurs due to malignant hypertension
Fibrinoid necrosis
Fibrinoid necrosis of the placental blood vessels occurs due to what?
Pre-eclampsia
