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==Types==
 
==Types==
===Granulomatous Inflammation===
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===[[Granulomatous Inflammation]]===
 
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*  Granulomatous inflammation is usually caused by organisms of low  virulence but great persistence, or by implanted foreign bodies.
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* Classically appears as a '''granuloma'''.
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** NOT a tumour, despite the suffix "-oma".
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**  A circumscribed sphere of chronic inflammatory cells enveloped by  poorly organised attempts at encapsulation by local connective tissue.
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* The differences between a granuloma and an abscess must be appreciated.
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** The fibrous envelope is never as well developed as that of an abscess.
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**  The inner contents are never as completely fluid as in an abscess.
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====Structure of a Granuloma====
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=====Central core=====
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* The central core which contains the agent.
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* The agent may be visible with H&E staining in section, e.g.
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** ''[[Actinobacillus lignieresii]]''
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*** The cause of "Wooden tongue" in cattle.
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*** Appears as a granule, with a central core of the bacterial colony surrounded by radiating eosinophilic "clubs".
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**** Clubs are considered to be formed from degenerating collagen and antigen-antibody complexes.
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** ''[[Actinomyces bovis]]''
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*** The cause of "Lumpy Jaw" in cattle.
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*** Forms granules containing bacteria and "clubs".
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** Fungal hyphae
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** Parasitic larvae
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** Foreign bodies
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* The agent might not be visible without being selectively stained.
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** E.g.  [[:Category:Mycobacterium species|''Mycobacterium tuberculosis'']] and ''[[Brucella abortus]]''.
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*** Stain using an acid-fast stain (Ziehl-Neelsen), or a modification.
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*** These organisms are intracellular in the macrophages.
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=====Chronic Inflammatory Cells=====
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* Outside the core is a substantial number of chronic inflammatory cells.
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** Mainly macrophages.
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*** Often appear as epithelioid cells.
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** Lymphocytes
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** Plasma cells.
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*  Neutrophils and necrotic remnants of cells can be quite prominent in  the granulomas of [[:Category:Actinobacillus  species|''Actinobacillus'']] and  [[:Category:Actinomyces|''Actinomyces'']] species.
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* Eosinophils are prominent in parasitic granulomas.
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* A scattered and variable number of Giant cells are often seen, but not always in every granuloma.
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=====Outer Envelope=====
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* The final layer is an outer envelope of incomplete fibrous tissue.
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* Giant cells can also be seen in this area.
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====Gross Appearance of Granulomas====
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* The cut surface of granulomas varies considerably;
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** Tuberculous granulomas tend to have solid whitish cores which are often calcified.
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*** Grate on the knife when cut through.
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** Parasitic granulomas are often greenish in colour due to the substantial numbers of eosinophils.
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*** Older ones are also often calcified.
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**  [[:Category:Actinobacillus species|''Actinobacillus'']] and  [[:Category:Actinomyces|''Actinomyces'']] species often have liquefied  cores due to the necrosis and [[Neutrophils|neutrophils]].
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*** I.e. they are purulent.
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*** May discharge to the surface along sinus tracts.
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*** The central core of bacteria and ‘clubs’ may appear as yellowish granules in this pus.
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**** Often called "sulphur granules".
      
===Granulation Tissue===
 
===Granulation Tissue===
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* Ulcers and open wounds may heal by granulation.
 
* Ulcers and open wounds may heal by granulation.
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[[Category:Chronic Inflammation]][[Category:To Do - Blood]]
 
===Lymphocytic Inflammation===
 
===Lymphocytic Inflammation===
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*#** Ee.g. [[:Category:Mycoplasmas|Mycoplasmosis]] in swine and calves.
 
*#** Ee.g. [[:Category:Mycoplasmas|Mycoplasmosis]] in swine and calves.
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[[Category:Chronic Inflammation]][[Category:To Do - Blood]]
 
[[Category:Inflammation]]
 
[[Category:Inflammation]]
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