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Colon (view source)

Revision as of 08:39, 31 July 2013

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→‎Microscopic colitis: split out collagenous colitis
(→‎Microscopic colitis: split out LC)
(→‎Microscopic colitis: split out collagenous colitis)
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:''Microscopic colitis'' may refer to a microscopic manifestation of an unspecified disease process that can be apparent macroscopically. This section links to a pair of diseases (''lymphocytic colitis'' and ''collagenous colitis'') that are considered to only have microscopic manifestations and characteristic clinical presentation.
:''Microscopic colitis'' may refer to a microscopic manifestation of an unspecified disease process that can be apparent macroscopically. This section links to a pair of diseases (''lymphocytic colitis'' and ''collagenous colitis'') that are considered to only have microscopic manifestations and characteristic clinical presentation.
{{Main|Lymphocytic colitis}}
{{Main|Lymphocytic colitis}}
 
{{Main|Collagenous colitis}}
===General===
Presentation:
*Chronic diarrhea, non-bloody.<ref name=medscape180664>URL: [http://emedicine.medscape.com/article/180664-overview http://emedicine.medscape.com/article/180664-overview]. Accessed on: 31 May 2010.</ref>
 
Notes:
*Clinical DDx includes [[irritable bowel syndrome]] - which has no or subtle histopathologic changes.
 
====Classification====
*Lymphocytic colitis (LC).
*Collagenous colitis (CC).
 
Note:
*Some believe that LC and CC are different time points in the same process-- but this is unproven.<ref name=medscape180664/>
 
====Epidemiology====
*Age: a disease of adults - usually 50s.
*Sex:
**LC males ~= females,<ref name=medscape180664/>
**CC females:males = 20:1.<ref name=medscape180664/>
*Drugs are associated with LC and CC.
**NSAIDs - posulated association/weak association,
**SSRIs (used primarily for depression) - moderate association, dependent on specific drug.
*Associated with autoimmune disorders - [[celiac disease]], [[diabetes mellitus]], [[thyroid]] disorders and [[arthritis]].<ref name=pmid19109861>{{cite journal |author=Tysk C, Bohr J, Nyhlin N, Wickbom A, Eriksson S |title=Diagnosis and management of microscopic colitis |journal=World J. Gastroenterol. |volume=14 |issue=48 |pages=7280-8 |year=2008 |month=December |pmid=19109861 |doi= |url=http://www.wjgnet.com/1007-9327/14/7280.asp}}</ref>
*No increased risk of colorectal carcinoma.<ref name=pmid19109861/>
 
====Treatment====
*Sometimes just follow-up.
*Steroids - budesonide -- short-term treatment.<ref name=pmid19109861/>
 
===Gross===
*As the name suggests, they are microscopic, i.e. endoscopic examination is normal.
 
===Microscopic===
====Collagenous colitis====
Features:
*Intraepithelial lymphocytes - '''important'''.
*Collagenous material in the lamina propria (pink on H&E) -- '''key feature'''.
**Can be demonstrated with a trichrome stain -- collagen = green on trichrome.
**Subepithelial collagen needs to be >= 10 micrometres thick for diagnosis.<ref name=pmid19109861/>
***8 micrometres is the diameter of a [[RBC]].
***The normal thickness of the subepithelial collagen is 3 micrometres.<ref name=pmid19109861/>
***Transverse colon usually thickest - in one series ~ 47 micrometres on average.<ref name=pmid10208468>{{Cite journal  | last1 = Offner | first1 = FA. | last2 = Jao | first2 = RV. | last3 = Lewin | first3 = KJ. | last4 = Havelec | first4 = L. | last5 = Weinstein | first5 = WM. | title = Collagenous colitis: a study of the distribution of morphological abnormalities and their histological detection. | journal = Hum Pathol | volume = 30 | issue = 4 | pages = 451-7 | month = Apr | year = 1999 | doi =  | PMID = 10208468 }}</ref>
**Thickening is usually patchy.<ref name=pmid1740280/>
**Thickening "follows the crypts from the surface" - useful for differentiating from tangential sections of the basement membrane.<ref name=bell>Bell, D. 4 Mar 2009.</ref>
**Collagen may envelope capillaries - useful to discern from basement membrane.<ref name=bell>Bell, D. 4 Mar 2009.</ref>
 
Notes:
*CC is typically more prominent in the proximal colon - may reflect concentration gradient of offending causitive agents.<ref name=pmid19109861/>
*Significant negative findings:<ref name=hopkins_cc_lc/>
**No [[PMN]]s.
**No crypt distortion.
*Thickened collagen band uncommon in rectum.<ref name=pmid1740280>{{Cite journal  | last1 = Tanaka | first1 = M. | last2 = Mazzoleni | first2 = G. | last3 = Riddell | first3 = RH. | title = Distribution of collagenous colitis: utility of flexible sigmoidoscopy. | journal = Gut | volume = 33 | issue = 1 | pages = 65-70 | month = Jan | year = 1992 | doi =  | PMID = 1740280 }}</ref>
 
====Images====
<gallery>
Image:Collagenous_colitis_-_intermed_mag.jpg | CC - intermed mag. (WC/Nephron)
Image:Collagenous_colitis_-_high_mag.jpg | CC - high mag. (WC/Nephron)
</gallery>
 
===Sign out===
<pre>
TRANSVERSE COLON, BIOPSY:
- COLLAGENOUS COLITIS.
</pre>
 
====Micro====
=====Collagenous colitis=====
The sections show colonic mucosa with abundant intraepithelial lymphocytes (>20 lymphocytes/100 surface epithelial cells). A prominent collagen band is apparent below the epithelium (>10 micrometres thick). The glandular architecture is within normal limits.
 
There are no granulomas. No neutrophilic cryptitis is apparent. The epithelium matures
appropriately to the surface.


==Diversion colitis==
==Diversion colitis==
Michael
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