Q. I can’t seem to get the different types of necrosis straight (liquefactive, fibrinoid, etc.). Any help?
A. There are basically six distinct patterns of necrosis. It’s important to know about these, because they can give you a clue as to why the tissue died. We’ll go through these in bullet form to make it easy to compare.
Coagulative
- See this in infarcts in any tissue (except brain)
- Due to loss of blood
- Gross: tissue is firm
- Micro: Cell outlines are preserved (cells look ghostly), and everything looks red
Liquefactive
- See this in infections and, for some unknown reason, in brain infarcts
- Due to lots of neutrophils around releasing their toxic contents, “liquefying” the tissue
- Gross: tissue is liquidy and creamy yellow (pus)
- Micro: lots of neutrophils and cell debris
Caseous
- See this in tuberculosis
- Due to the body trying to wall off and kill the bug with macrophages
- Gross: White, soft, cheesy-looking (“caseous”) material
- Micro: fragmented cells and debris surrounded by a collar of lymphocytes and macrophages (granuloma)
Fat necrosis
- See this in acute pancreatitis
- Damaged cells release lipases, which split the triglyceride esters within fat cells
- Gross: chalky, white areas from the combination of the newly-formed free fatty acids with calcium (saponification)
- Micro: shadowy outlines of dead fat cells (see image at the top); sometimes there is a bluish cast from the calcium deposits, which are basophilic
Fibrinoid necrosis
- See this in immune reactions in vessels
- Immune complexes (antigen-antibody complexes) and fibrin are deposited in vessel walls
- Gross: changes too small to see grossly
- Micro: vessel walls are thickened and pinkish-red (called “fibrinoid” because the deposits look like fibrin deposits)
Gangrenous necrosis
- See this when an entire limb loses blood supply and dies (usually the lower leg)
- This isn’t really a different kind of necrosis, but people use the term clinically so it’s worth knowing about
- Gross: skin looks black and dead; underlying tissue is in varying stages of decomposition
- Micro: initially there is coagulative necrosis from the loss of blood supply (this stage is called “dry gangrene”); if bacterial infection is superimposed, there is liquefactive necrosis (this stage is called “wet gangrene”)
THANK YOU VERY MUCH! I’m much more prepared now for my upcoming mid-term examination. ^^
It was really helpful!thanks very much
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I hate hate hate this subject
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Thank u for such a good information
I feel your pain, Sara! Maybe we can help make it less horrible.
its very helpful
Tanks so much it’s very helpful.
Nice one. bt why is apoptosis called programmed cell death?
Because it is controlled by gene products encoded by the cell’s own DNA. Cells have this pathway available in case they need it – and when it is triggered, it happens the same way every time (it’s programmed).
Thanks
thanks…very helpful.
Thank you! You don’t know how much it helps me!! 🙂
Thanks a lot. It is essay to memorize and write in exam.
Thanks alot its very helpful for my upcoming end exams
EZ af
Thank you
thanks a lot
Thank you very much!!!! God bless you
thanks for you sir
Very helpful to me.
Really helpful
thanks i have learnt alot…be blessed
It’s really helpful
Thanks it’s helpful
Would you consider adding fat necrosis to this list?
Yes – it’s in there! It’s the fourth one down 🙂
how lucky I’m! at least I have found a place where I can learn pathology in a interesting way…
thank you soo much sir
very helpful………..everything in one bullet!
It was of so much help .thanks!
This is so interesting and easy to understand. This has been very helpful, thank you so much.
Thanks so much it really helped me in my exam
Yay!!
thank you very much! it really clarified my confusion