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.
- 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
- 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
- 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)
- 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 above); sometimes there is a bluish cast from the calcium deposits, which are basophilic
- 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)
- 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”)
Tagsacute leukemia acute lymphoblastic leukemia acute myeloid leukemia acute promyelocytic leukemia Add new tag anemia b cells blood smear bone marrow brain tumors carcinoma cases chronic myelofibrosis chronic myeloid leukemia chronic myeloproliferative disorders coagulation cortisol cytochemistry cytogenetics essential thrombocythemia heart hemophilia immunology infection inflammation kaplan kidney laboratory tests lymphocyte lymphocytes lymphoma macrophages neoplasia neutrophil normal photoblog polycythemia vera red blood cells red cells sickle cell anemia skin squamous cell carcinoma stains student questions t cells
- Ephriam Bam said Thanks very much for your simple and clear explanation!
- Marina P said Professor Thomas Renne from Sweden and his group conduct research on the topic of FXII, I found it m...
- sachini said Very important this one.thank you
- Jeevanshu Dhawan said That is the most simple explanation I have read till date. Thanks.
- pooja said Great explanation. Thank you
- Sandhya said Kristine, you are a teacher non-pareil !
- Lilah said Thanks looking forward for the bites
- Kristine said Hi Kanopo – it’s okay! Leukemias and lymphomas can be confusing, for sure. To answer you...
- Kristine said There are a million microliters in a liter (1 L = 1,000,000 microliters). So 4,000 cells/microliter...
- VAISHALI said STILL I DONT UNDERSTAND-LOWER NORMAL RANGE IS 4.0 x 103/μL THAT MEANS IN 1uL THERE ARE 4000 CELLS,SO...
- Devender Singh said good
- LILAH said SOOO GOOD