Difference between revisions of "Colon"

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===Microscopic===
===Microscopic===
Features:
Features:
*Typically more prominent in the cecum and proximal colon.<ref name=pmid18666316/>
*Brown granular pigment - in the lamina propria.
 
**Typically more prominent in the cecum and proximal colon.<ref name=pmid18666316/>
DDx of brown pigment:
*Lipofuscin - comes with age (can be demonstrated with a ''Kluver-Barrera stain''<ref>URL: [http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exkluvbarr.htm http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exkluvbarr.htm]. Accessed on: 5 May 2010.</ref>).
**Melanosis coli.
*Old haemorrhage, i.e. hemosiderin-laden macrophages (may be demonstrated with ''Prussian blue stain''<ref>URL: [http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exprussb.htm http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exprussb.htm]. Accessed on: 5 May 2010.</ref>).
*Melanin (from melanocytes) - rare in colon (may be demonstrated with a ''Fontana-Masson stain''<ref>URL: [http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exfontana.htm http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exfontana.htm]. Accessed on: 5 May 2010.</ref> -- though not so useful in the GI tract).
*Foriegn material (e.g. tattoo pigment) - not seen in GI tract.


Images:
Images:
*[http://commons.wikimedia.org/wiki/File:Melanosis_coli_high_mag.jpg Melanosis coli - high mag. (WC)].
*[http://commons.wikimedia.org/wiki/File:Melanosis_coli_high_mag.jpg Melanosis coli - high mag. (WC)].
*[http://commons.wikimedia.org/wiki/File:Melanosis_coli_low_mag.jpg Melanosis coli - low mag. (WC)].
*[http://commons.wikimedia.org/wiki/File:Melanosis_coli_low_mag.jpg Melanosis coli - low mag. (WC)].
Notes:
*DDx of brown pigment:
**Lipofuscin - comes with age (can be demonstrated with a ''Kluver-Barrera stain''<ref>URL: [http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exkluvbarr.htm http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exkluvbarr.htm]. Accessed on: 5 May 2010.</ref>).
***Melanosis coli.
**Old haemorrhage, i.e. hemosiderin-laden macrophages (may be demonstrated with ''Prussian blue stain''<ref>URL: [http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exprussb.htm http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exprussb.htm]. Accessed on: 5 May 2010.</ref>).
**Melanin (from melanocytes) - rare in colon (may be demonstrated with a ''Fontana-Masson stain''<ref>URL: [http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exfontana.htm http://education.vetmed.vt.edu/curriculum/VM8054/labs/Lab2/Examples/exfontana.htm]. Accessed on: 5 May 2010.</ref> -- though not so useful in the GI tract).
**Foreign material (e.g. tattoo pigment) - not seen in GI tract.
===Stains===
*Can be demonstrated with a [[PAS stain]].<ref name=pmid9283862>{{cite journal |author=Benavides SH, Morgante PE, Monserrat AJ, Zárate J, Porta EA |title=The pigment of melanosis coli: a lectin histochemical study |journal=Gastrointest. Endosc. |volume=46 |issue=2 |pages=131–8 |year=1997 |month=August |pmid=9283862 |doi= |url=}}</ref>


==Microscopic colitis==
==Microscopic colitis==
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