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[[Image:Small intestine low mag.jpg|thumb|250px|right|Small bowel mucosa. [[H&E stain]].]] | |||
The '''small intestine''', also '''small bowel''', is a relatively well-behaved piece of machinery from the perspective of [[pathology]]. It is uncommonly affected by malignancies, relative to its length when compared to the [[colon]] and [[rectum]]. | The '''small intestine''', also '''small bowel''', is a relatively well-behaved piece of machinery from the perspective of [[pathology]]. It is uncommonly affected by malignancies, relative to its length when compared to the [[colon]] and [[rectum]]. | ||
=Normal= | =Normal small bowel= | ||
==Anatomy== | *[[AKA]] ''normal small intestine''. | ||
===Anatomy=== | |||
Consists of three segments: | Consists of three segments: | ||
*Duodenum | *[[Duodenum]] - can be divided into four parts. | ||
*Jejunum. | *Jejunum. | ||
*Ileum. | *Ileum. | ||
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The later two parts keep ''general surgeons'' awake at night (quite literally) 'cause they get obstructed and need urgent operations. | The later two parts keep ''general surgeons'' awake at night (quite literally) 'cause they get obstructed and need urgent operations. | ||
====Length==== | |||
*Normal length of small bowel = 3-8 metres.<ref name=pmid10422101>{{Cite journal | last1 = Nightingale | first1 = JM. | title = Management of patients with a short bowel. | journal = Nutrition | volume = 15 | issue = 7-8 | pages = 633-7 | month = | year = | doi = | PMID = 10422101 }}</ref> | |||
"Short": | |||
* | *Less than 200 cm = ''short bowel syndrome''.<ref name=pmid20709285>{{Cite journal | last1 = Donohoe | first1 = CL. | last2 = Reynolds | first2 = JV. | title = Short bowel syndrome. | journal = Surgeon | volume = 8 | issue = 5 | pages = 270-9 | month = Oct | year = 2010 | doi = 10.1016/j.surge.2010.06.004 | PMID = 20709285 }}</ref><ref name=pmid16207689>{{Cite journal | last1 = Matarese | first1 = LE. | last2 = O'Keefe | first2 = SJ. | last3 = Kandil | first3 = HM. | last4 = Bond | first4 = G. | last5 = Costa | first5 = G. | last6 = Abu-Elmagd | first6 = K. | title = Short bowel syndrome: clinical guidelines for nutrition management. | journal = Nutr Clin Pract | volume = 20 | issue = 5 | pages = 493-502 | month = Oct | year = 2005 | doi = | PMID = 16207689 }}</ref> | ||
**Less than 100 cm usu. requires parenteral nutrition.<ref name=pmid11873098>{{Cite journal | last1 = Sundaram | first1 = A. | last2 = Koutkia | first2 = P. | last3 = Apovian | first3 = CM. | title = Nutritional management of short bowel syndrome in adults. | journal = J Clin Gastroenterol | volume = 34 | issue = 3 | pages = 207-20 | month = Mar | year = 2002 | doi = | PMID = 11873098 }}</ref> | |||
===Histology=== | |||
==Histology== | |||
{{main|Gastrointestinal pathology}} | {{main|Gastrointestinal pathology}} | ||
The ''[[Gastrointestinal pathology]]'' article covers basic histology of the GI tract. | The ''[[Gastrointestinal pathology]]'' article covers basic histology of the GI tract. | ||
=[[Immunohistochemistry]]= | ===[[Immunohistochemistry]]=== | ||
*Normal small intestine is CK20 +ve... while adenocarcinoma of the small bowel may be CK20 -ve.<ref>{{cite journal |author=Chen ZM, Wang HL |title=Alteration of cytokeratin 7 and cytokeratin 20 expression profile is uniquely associated with tumorigenesis of primary adenocarcinoma of the small intestine |journal=Am. J. Surg. Pathol. |volume=28 |issue=10 |pages=1352–9 |year=2004 |month=October |pmid=15371952 |doi= |url=}}</ref> | *Normal small intestine is CK20 +ve... while adenocarcinoma of the small bowel may be CK20 -ve.<ref>{{cite journal |author=Chen ZM, Wang HL |title=Alteration of cytokeratin 7 and cytokeratin 20 expression profile is uniquely associated with tumorigenesis of primary adenocarcinoma of the small intestine |journal=Am. J. Surg. Pathol. |volume=28 |issue=10 |pages=1352–9 |year=2004 |month=October |pmid=15371952 |doi= |url=}}</ref> | ||
===Sign out=== | |||
<pre> | |||
Small Bowel, Biopsy: | |||
- Small bowel mucosa within normal limits. | |||
</pre> | |||
<pre> | |||
Terminal Ileum, Biopsy: | |||
- Small bowel mucosa within normal limits. | |||
</pre> | |||
<pre> | |||
Terminal Ileum, Biopsy: | |||
- Small bowel mucosa with morphologically benign lymphoid aggregates, negative for significant pathology. | |||
</pre> | |||
====Roux-en-Y gastric bypass==== | |||
{{Main|Obese}} | |||
{{Main|Roux-en-Y gastric bypass}} | |||
====Block letters==== | |||
<pre> | |||
SMALL BOWEL, BIOPSY: | |||
- SMALL BOWEL MUCOSA WITHIN NORMAL LIMITS. | |||
</pre> | |||
<pre> | |||
TERMINAL ILEUM, BIOPSY: | |||
- SMALL BOWEL MUCOSA WITHIN NORMAL LIMITS. | |||
</pre> | |||
<pre> | |||
TERMINAL ILEUM, BIOPSY: | |||
- SMALL BOWEL MUCOSA WITH MORPHOLOGICAL BENIGN LYMPHOID AGGREGATES, NO SIGNIFICANT PATHOLOGY. | |||
</pre> | |||
=The segments= | =The segments= | ||
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*Suspected giardia. | *Suspected giardia. | ||
*Suspected [[celiac sprue]]. | *Suspected [[celiac sprue]]. | ||
*Is this cancer? | *Is this [[cancer]]? | ||
*Looks normal... want to dot the i's and cross the t's. | *Looks normal... want to dot the i's and cross the t's. | ||
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==Ileum== | ==Ileum== | ||
*This is seen occasionally -- often in the context of IBD and more specifically [[Crohn's disease]]. | *This is seen occasionally -- often in the context of [[IBD]] and more specifically [[Crohn's disease]]. | ||
*Crohn's disease | **[[Crohn's disease]] and[[ulcerative colitis]] are discussed in their respective articles. | ||
=== | =Specific diagnoses= | ||
General | ==Ileitis== | ||
* | :''Active ileitis'' and ''acute ileitis'' redirect here. | ||
* | :This deals with nonspecific ileitis. | ||
* | ===General=== | ||
*Common. | |||
===Microscopic=== | |||
Features: | |||
*Intraepithelial [[neutrophil]]s. | |||
DDx: | |||
*[[Crohn's disease]]. | |||
*Infectious ileitis. | |||
**[[Tuberculosis]]. | |||
*Benign ileum - may have focal intra-epithelial lymphocytes associated with lamina propria lymphoid nodules. | |||
*[[NSAID enteropathy]].<ref name=pmid20532706>{{Cite journal | last1 = Dilauro | first1 = S. | last2 = Crum-Cianflone | first2 = NF. | title = Ileitis: when it is not Crohn's disease. | journal = Curr Gastroenterol Rep | volume = 12 | issue = 4 | pages = 249-58 | month = Aug | year = 2010 | doi = 10.1007/s11894-010-0112-5 | PMID = 20532706 }}</ref> | |||
====Images==== | |||
<gallery> | |||
Image: Mild ileitis -- very low mag.jpg | Ileitis - very low mag. (WC) | |||
Image: Mild ileitis -- low mag.jpg | Ileitis - low mag. (WC) | |||
Image: Mild ileitis -- intermed mag.jpg | Ileitis - intermed. mag. (WC) | |||
Image: Mild ileitis -- high mag.jpg | Ileitis - high mag. (WC) | |||
</gallery> | |||
===Sign out=== | |||
<pre> | |||
Terminal Ileum, Biopsy: | |||
- Small bowel with moderate active inflammation, marked villous blunting, basal plasmacytosis | |||
and prominent eosinophils, see comment. | |||
- NEGATIVE for granulomas. | |||
- NEGATIVE for dysplasia. | |||
Comment: | |||
The inflammation is nonspecific; it could be due to infection, inflammatory bowel disease (especially Crohn's disease), ischemia, or therapy/drugs. Clinical correlation is required. | |||
</pre> | |||
==Small bowel obstruction== | |||
*Abbreviated ''SBO''. | |||
{{Main|Small bowel obstruction}} | |||
==Small bowel neoplasms== | ==Small bowel neoplasms== | ||
*Adenocarcinoma - like colonic. | *Adenocarcinoma - like colonic. | ||
*Adenosquamous carcinoma. | *[[Adenosquamous carcinoma]]. | ||
* | *[[Neuroendocrine tumour]]. | ||
*[[GIST]]. | *[[GIST]]. | ||
*[[Schwannoma]]. | *[[Schwannoma]]. | ||
**Classically have a ''peripheral lymphoid cuff''.<ref name=pmid15728600>{{cite journal |author=Levy AD, Quiles AM, Miettinen M, Sobin LH |title=Gastrointestinal schwannomas: CT features with clinicopathologic correlation |journal=AJR Am J Roentgenol |volume=184 |issue=3 |pages=797–802 |year=2005 |month=March |pmid=15728600 |doi= |url=http://www.ajronline.org/cgi/content/full/184/3/797}}</ref> | **Classically have a ''peripheral lymphoid cuff''.<ref name=pmid15728600>{{cite journal |author=Levy AD, Quiles AM, Miettinen M, Sobin LH |title=Gastrointestinal schwannomas: CT features with clinicopathologic correlation |journal=AJR Am J Roentgenol |volume=184 |issue=3 |pages=797–802 |year=2005 |month=March |pmid=15728600 |doi= |url=http://www.ajronline.org/cgi/content/full/184/3/797}}</ref> | ||
== | ==Mechanical small bowel perforation== | ||
:See ''[[mechanical bowel perforation]]''. | |||
==Ileal nodular lymphoid hyperplasia== | |||
*[[AKA]] ''nodular lymphoid hyperplasia of the terminal ileum''. | |||
===General=== | ===General=== | ||
*Strictures associated with chronic NSAID use.<ref name=pmid1481311>{{cite journal |author=McCune KH, Allen D, Cranley B |title=Small bowel diaphragm disease--strictures associated with non-steroidal anti-inflammatory drugs |journal=Ulster Med J |volume=61 |issue=2 |pages=182–4 |year=1992 |month=October |pmid=1481311 |pmc=2448949 |doi= |url=}}</ref> | *An uncommon diagnosis. | ||
*May be associated with hypogammaglobulinemia.<ref name=pmid8782302>{{cite journal |author=Yamaue H, Tanimura H, Ishimoto K, Morikawa Y, Kakudo K |title=Nodular lymphoid hyperplasia of the terminal ileum: report of a case and the findings of an immunological analysis |journal=Surg. Today |volume=26 |issue=6 |pages=431-4 |year=1996 |pmid=8782302 |doi= |url=}}</ref> | |||
===Gross=== | |||
*Mucosal nodularity. | |||
===Microscopic=== | |||
Features: | |||
*Lymphoid nodules +/- germinal centre formation. | |||
Note: | |||
*Tingible body macrophages suggest an aggregate is benign. | |||
DDx: | |||
*[[MALT lymphoma]]. | |||
*[[Mantle cell lymphoma]]. | |||
*Other lymphomas. | |||
===IHC=== | |||
*[[CD20]] and CD3 - mixed population of lymphocytes. | |||
*[[CD23]] - follicular dendritic cells. | |||
*Cyclin D1 -ve. | |||
Note: | |||
*IHC should be used if there is: | |||
**Clinical suspicion. | |||
**Histologic suspicion - either: | |||
***Sheets of lymphocytes without apparent germinal centre formation in a larger area (~ 2 mm). | |||
***[[Lymphoepithelial lesion]]s. | |||
===Sign out=== | |||
<pre> | |||
TERMINAL ILEUM, BIOPSY: | |||
- SMALL BOWEL MUCOSA WITH LYMPHOID NODULES WITH GERMINAL CENTRE | |||
FORMATION -- NO SIGNIFICANT PATHOLOGY. | |||
- NEGATIVE FOR ILEITIS. | |||
</pre> | |||
<pre> | |||
TERMINAL ILEUM, BIOPSY: | |||
- SMALL BOWEL MUCOSA WITH LYMPHOID HYPERPLASIA -- NO SIGNIFICANT PATHOLOGY. | |||
</pre> | |||
====Micro==== | |||
The sections show small bowel mucosa with lymphoid hyperplasia. | |||
Immunostains for CD3 and CD20 show a mixed population of lymphocytes. A CD23 immunostain shows follicular dendritic cell networks. A cyclin D1 immunostain is negative. | |||
=====Alternate===== | |||
Immunostains for CD3 and CD20 show a mixed population of lymphocytes, with CD20 cells predominating. A cyclin D1 immunostain is negative. A CD23 immunostain shows follicular dendritic cell networks. | |||
==Multiple lymphomatous polyposis== | |||
*Abbreviated ''MLP''. | |||
*[[AKA]] ''lymphomatous polyposis''. | |||
===General=== | |||
*MLP is classically due to ''[[mantle cell lymphoma]]''.<ref name=pmid20206107>{{Cite journal | last1 = Ruskoné-Fourmestraux | first1 = A. | last2 = Audouin | first2 = J. | title = Primary gastrointestinal tract mantle cell lymphoma as multiple lymphomatous polyposis. | journal = Best Pract Res Clin Gastroenterol | volume = 24 | issue = 1 | pages = 35-42 | month = Feb | year = 2010 | doi = 10.1016/j.bpg.2009.12.001 | PMID = 20206107 }}</ref> | |||
**May be due to other lymphomas, e.g. [[follicular lymphoma]].<ref>URL: [http://www.pathmax.com/gilymph.html http://www.pathmax.com/gilymph.html]. Accessed on: 1 April 2012.</ref> | |||
===Microscopic=== | |||
Features: | |||
*Lymphoid nodules consisting of (small) atypical lymphocytes with an abnormal architecture. | |||
===IHC=== | |||
See ''[[small cell lymphomas]]''. | |||
==Small bowel diaphragm disease== | |||
*[[AKA]] ''diaphragm disease''. | |||
===General=== | |||
*Strictures associated with chronic [[NSAID]] use.<ref name=pmid1481311>{{cite journal |author=McCune KH, Allen D, Cranley B |title=Small bowel diaphragm disease--strictures associated with non-steroidal anti-inflammatory drugs |journal=Ulster Med J |volume=61 |issue=2 |pages=182–4 |year=1992 |month=October |pmid=1481311 |pmc=2448949 |doi= |url=}}</ref> | |||
*Usu. mid to distal ileum. | *Usu. mid to distal ileum. | ||
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**+/-Distortion of adjacent muscularis propria. | **+/-Distortion of adjacent muscularis propria. | ||
**+/-Adjacent mucosal erosions/granulation tissue. | **+/-Adjacent mucosal erosions/granulation tissue. | ||
DDx: | |||
*Cryptogenic multifocal ulcerous stenosing enteritis.<ref>{{Cite journal | last1 = Chung | first1 = SH. | last2 = Jo | first2 = Y. | last3 = Ryu | first3 = SR. | last4 = Ahn | first4 = SB. | last5 = Son | first5 = BK. | last6 = Kim | first6 = SH. | last7 = Park | first7 = YS. | last8 = Hong | first8 = YO. | title = Diaphragm disease compared with cryptogenic multifocal ulcerous stenosing enteritis. | journal = World J Gastroenterol | volume = 17 | issue = 23 | pages = 2873-6 | month = Jun | year = 2011 | doi = 10.3748/wjg.v17.i23.2873 | PMID = 21734797 }}</ref> (???) | |||
*[[Crohn's disease]]. | |||
==Meckel diverticulum== | |||
{{Main|Meckel diverticulum}} | |||
==Ischemic enteritis== | |||
{{Main|Ischemic enteritis}} | |||
=Weird stuff= | |||
==Autoimmune enteropathy== | |||
*Abbreviated as ''AIE''. | |||
{{Main|Autoimmune enteropathy}} | |||
=See also= | =See also= |
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