Difference between revisions of "Vermiform appendix"
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'''Vermiform appendix''' is | The '''Vermiform appendix''' is, usually, just called ''appendix''. Taking it out is the bread 'n butter of general surgery. | ||
The appendix is a vestigial structure that is thought to have arisen from a larger cecum. Larger cecae are often seen in herbivores and thought to facilitate better digestion of plant matter.<ref>Dawkins R. The Greatest Show on Earth: The Evidence for Evolution. ISBN 978-1416594789.</ref> | |||
==Acute appendicitis== | ==Acute appendicitis== | ||
| Line 37: | Line 39: | ||
|- | |- | ||
|} | |} | ||
*LAMN = low-grade appendiceal mucinous neoplasm | *LAMN = low-grade appendiceal mucinous neoplasm. | ||
*LAMN ex-appy = LAMN with extra-appendiceal spread | *LAMN ex-appy = LAMN with extra-appendiceal spread. | ||
*MACA = mucinous adenocarcinoma | *MACA = mucinous adenocarcinoma. | ||
===Benign mucinous tumour=== | ===Benign mucinous tumour=== | ||
| Line 62: | Line 64: | ||
==Granulomatous appendicitis== | ==Granulomatous appendicitis== | ||
Most common cause: | |||
Most common: | |||
*Yersinia appendicitis.<ref name=pmid11257626>{{cite journal |author=Lamps LW, Madhusudhan KT, Greenson JK, ''et al.'' |title=The role of Yersinia enterocolitica and Yersinia pseudotuberculosis in granulomatous appendicitis: a histologic and molecular study |journal=Am. J. Surg. Pathol. |volume=25 |issue=4 |pages=508–15 |year=2001 |month=April |pmid=11257626 |doi= |url=}}</ref> | *Yersinia appendicitis.<ref name=pmid11257626>{{cite journal |author=Lamps LW, Madhusudhan KT, Greenson JK, ''et al.'' |title=The role of Yersinia enterocolitica and Yersinia pseudotuberculosis in granulomatous appendicitis: a histologic and molecular study |journal=Am. J. Surg. Pathol. |volume=25 |issue=4 |pages=508–15 |year=2001 |month=April |pmid=11257626 |doi= |url=}}</ref> | ||
| Line 76: | Line 75: | ||
*Foreign body reaction. | *Foreign body reaction. | ||
*Interval (delayed) appendectomy. | *Interval (delayed) appendectomy. | ||
===Microscopic=== | |||
Features: | |||
*Granulomas. | |||
==Goblet cell carcinoid== | ==Goblet cell carcinoid== | ||
| Line 112: | Line 115: | ||
Notes: | Notes: | ||
*Nice review of stains in Pahlavan and Kanthan.<ref name=pmid15967038>{{cite journal |author=Pahlavan PS, Kanthan R |title=Goblet cell carcinoid of the appendix |journal=World J Surg Oncol |volume=3 |issue= |pages=36 |year=2005 |month=June |pmid=15967038 |pmc=1182398 |doi=10.1186/1477-7819-3-36 |url=http://wjso.com/content/3/1/36}}</ref> | *Nice review of stains in Pahlavan and Kanthan.<ref name=pmid15967038>{{cite journal |author=Pahlavan PS, Kanthan R |title=Goblet cell carcinoid of the appendix |journal=World J Surg Oncol |volume=3 |issue= |pages=36 |year=2005 |month=June |pmid=15967038 |pmc=1182398 |doi=10.1186/1477-7819-3-36 |url=http://wjso.com/content/3/1/36}}</ref> | ||
==See also== | ==See also== | ||
*[[Colon]] | *[[Colon]]. | ||
*[[Gastrointestinal pathology]] | *[[Gastrointestinal pathology]]. | ||
==References== | ==References== | ||
Revision as of 12:02, 13 May 2010
The Vermiform appendix is, usually, just called appendix. Taking it out is the bread 'n butter of general surgery.
The appendix is a vestigial structure that is thought to have arisen from a larger cecum. Larger cecae are often seen in herbivores and thought to facilitate better digestion of plant matter.[1]
Acute appendicitis
Gross
- Serosal surface dull.
- May be perforated.
- +/-Fibrinous exudate.
Micro. definition
- Neutrophils in the muscularis propria.
Tumours of the appendix
Adenocarcinoma
- Like colorectal adenocarcinoma - see colon.
Mucinous tumour
General
- classification is controversial.
- the controversy centres on whether to call all mucinous tumours outside of the appendix adenocarcinoma - regardless of whether they have atypia & show invasion.
- in women - an ovarian primary must be excluded.
- concurrent bilateral ovarian tumours suggests the tumour originated from the appendix and spread to the ovaries.
Classification[2]
- benign - low grade mucinous tumour.
- borderline - mucinous tumour of uncertain malignant potential or borderline mucinous tumour.
- malignant - mucinous adenocarcinoma.
Five year survival[2]
| 5 year survival | |
| LAMN | 100% |
| LAMN ex-appy | 86% |
| MACA | 44% |
- LAMN = low-grade appendiceal mucinous neoplasm.
- LAMN ex-appy = LAMN with extra-appendiceal spread.
- MACA = mucinous adenocarcinoma.
Benign mucinous tumour
Micro.
- Epithelium forms tufts - vaguely resemble serrations, i.e. the saw-tooth pattern in hyperplastic polyps.
- Single layer of epithelium.
- Mucin contained (inside appendix only).
Negatives
- No marked nuclear atypia.
- No invasion into the lamina propria.
Borderline mucinous tumour
Micro.
- Same as benign, but mucin outside of the appendix.
- Cells in mucin, i.e. cellular mucin.
Malignant mucinous tumour
Micro.
- Marked nuclear pleomorphism.
- Invasion into the wall.
Granulomatous appendicitis
Most common cause:
- Yersinia appendicitis.[3]
DDx:[4]
- Yersinia appendicitis.[3]
- Yersinia = gram negative rod.
- Other micro-organism (TB, fungus).
- Crohn's disease.
- Sarcoidosis.
- Foreign body reaction.
- Interval (delayed) appendectomy.
Microscopic
Features:
- Granulomas.
Goblet cell carcinoid
- Rare appendiceal tumour that typically has an aggressive course vis-a-vis other appendiceal carcinoid.[5]
- AKA crypt cell carcinoma - probably a better descriptor.[5]
- Mixed (biphasic) tumour with endocrine and exocrine features.
Histology
Features:[6]
- Mixed neuroendocrine-nonneuroendocrine tumour;[7] features of both carcinoid and adenocarcinoma.[6]
- Archictecture: cells arranged in nests or clusters without a lumen.
- Location: deep to the intestinal crypts (crypts of Lieberkühn); usually do not involve the mucosa.
- Cytoplasm distended with mucin.
- DNA: crescentic nucleus (similar to in signet-ring cells).
- +/-Multinucleation.
- +/-High mitotic rate.
- Usually minimal nuclear atypia.
Stains
- Mucin stains +ve:
- Mucicarmine, perodic acid-Schiff diastase (PAS-D), alician blue.
IHC
- Classic neuroendocrine markers:
- Synaptophysin +ve.
- Chromogranin +ve.
- S100 +ve.
- NSE +ve.
- Serotonin +ve.
Keratins:
- Usually CK20 +ve > CK7 +ve.
- CEA +ve (membrane).
Notes:
- Nice review of stains in Pahlavan and Kanthan.[6]
See also
References
- ↑ Dawkins R. The Greatest Show on Earth: The Evidence for Evolution. ISBN 978-1416594789.
- ↑ 2.0 2.1 Misdraji J, Yantiss RK, Graeme-Cook FM, Balis UJ, Young RH (August 2003). "Appendiceal mucinous neoplasms: a clinicopathologic analysis of 107 cases". Am. J. Surg. Pathol. 27 (8): 1089–103. PMID 12883241. http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?issn=0147-5185&volume=27&issue=8&spage=1089.
- ↑ 3.0 3.1 Lamps LW, Madhusudhan KT, Greenson JK, et al. (April 2001). "The role of Yersinia enterocolitica and Yersinia pseudotuberculosis in granulomatous appendicitis: a histologic and molecular study". Am. J. Surg. Pathol. 25 (4): 508–15. PMID 11257626.
- ↑ http://granuloma.homestead.com/appendicitis.html
- ↑ 5.0 5.1 PMID 18042066.
- ↑ 6.0 6.1 6.2 Pahlavan PS, Kanthan R (June 2005). "Goblet cell carcinoid of the appendix". World J Surg Oncol 3: 36. doi:10.1186/1477-7819-3-36. PMC 1182398. PMID 15967038. http://wjso.com/content/3/1/36. Cite error: Invalid
<ref>tag; name "pmid15967038" defined multiple times with different content Cite error: Invalid<ref>tag; name "pmid15967038" defined multiple times with different content - ↑ PMID 17684764.