Difference between revisions of "Small intestine"
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The '''small bowel''' is a relatively well-behaved piece of machinery from the perspective of pathology. It is uncommonly affected by malignancies. | The '''small bowel''' is a relatively well-behaved piece of machinery from the perspective of pathology. It is uncommonly affected by malignancies. | ||
==Anatomy== | ==Anatomy== | ||
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In the context of bowel obstructions and IBD, pathologists often see resected stomas (that were put in place emergently). These specimens are usually fairly straight forward. | In the context of bowel obstructions and IBD, pathologists often see resected stomas (that were put in place emergently). These specimens are usually fairly straight forward. | ||
==[[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> | |||
==Histology== | ==Histology== | ||
Revision as of 05:27, 27 December 2010
The small bowel is a relatively well-behaved piece of machinery from the perspective of pathology. It is uncommonly affected by malignancies.
Anatomy
Consists of three segments:
- Duodenum (which can be divided into four parts).
- Jejunum.
- Ileum.
The later two parts keep general surgeons awake at night (quite literally) 'cause they get obstructed and need urgent operations.
The usual causes of bowel obstruction (large & small) are (mnemonic) SHAVING:
- Strictures (think IBD).
- Hernias.
- Adhesions.
- Volvulus.
- Intussusception.
- Neoplasia.
- Gallstone ileus.
- Adhesions > hernias > neoplasms.
In the context of bowel obstructions and IBD, pathologists often see resected stomas (that were put in place emergently). These specimens are usually fairly straight forward.
Immunohistochemistry
- Normal small intestine is CK20 +ve... while adenocarcinoma of the small bowel may be CK20 -ve.[3]
Histology
Main article: Gastrointestinal pathology
Duodenum
Main article: Duodenum
The duodenum is often biopsied by gastroenterologists.
Common reasons for biopsy:
- Suspected giardia.
- Suspected celiac sprue.
- Is this cancer?
- Looks normal... want to dot the i's and cross the t's.
Jejunum
- Uncommonly seen by pathologists.
- May be seen in the context of a resection done for a bowel obstruction.
Ileum
- This is seen occasionally -- often in the context of IBD and more specifically Crohn's disease.
- Crohn's disease (and ulcerative colitis) is discussed in the colon article.
Nodular lymphoid hyperplasia
General
- An uncommon diagnosis
- Prominent lymphoid follicles
- May be assoc. with hypogammaglobulinemia.[4]
Small bowel neoplasms
- Adenocarcinoma - like colonic.
- Adenosquamous carcinoma.
- Neuroendocine tumour.
- GIST.
- Schwannoma.
- Classically have a peripheral lymphoid cuff.[5]
See also
References
- ↑ http://www.emedicine.com/EMERG/topic66.htm
- ↑ TN 2007 GS21
- ↑ Chen ZM, Wang HL (October 2004). "Alteration of cytokeratin 7 and cytokeratin 20 expression profile is uniquely associated with tumorigenesis of primary adenocarcinoma of the small intestine". Am. J. Surg. Pathol. 28 (10): 1352–9. PMID 15371952.
- ↑ Yamaue H, Tanimura H, Ishimoto K, Morikawa Y, Kakudo K (1996). "Nodular lymphoid hyperplasia of the terminal ileum: report of a case and the findings of an immunological analysis". Surg. Today 26 (6): 431-4. PMID 8782302.
- ↑ Levy AD, Quiles AM, Miettinen M, Sobin LH (March 2005). "Gastrointestinal schwannomas: CT features with clinicopathologic correlation". AJR Am J Roentgenol 184 (3): 797–802. PMID 15728600. http://www.ajronline.org/cgi/content/full/184/3/797.