Difference between revisions of "Vermiform appendix"

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VERMIFORM APPENDIX WITHIN NORMAL LIMITS.
VERMIFORM APPENDIX WITHIN NORMAL LIMITS.
</pre>
</pre>
Note:
*This is for a normal appendix within a larger operation. The article ''[[negative appendectomy]]'' deals with a normal appearing appendix that was removed for presumed appendicitis.


==Negative appendectomy==
==Negative appendectomy==
===General===
{{Main|Negative appendectomy}}
*Common.
An appendectomy done for presumed [[acute appendicitis]] that is pathologically within normal limits
*Use for quality control among general surgeons.{{fact}}
 
===Gross===
See ''[[normal vermiform appendix]]''.
 
===Microscopic===
See ''[[normal vermiform appendix]]''.
 
Notes:
*Should be ''[[submitted in total]]''.
 
===Sign out===
<pre>
VERMIFORM APPENDIX, APPENDECTOMY:
- APPENDIX NEGATIVE FOR ACUTE APPENDICITIS AND NEGATIVE FOR ACUTE PERIAPPENDICITIS.
</pre>
 
<pre>
VERMIFORM APPENDIX, APPENDECTOMY:
- APPENDIX WITH LYMPHOID HYPERPLASIA AND FOCAL MUCOSAL EROSIONS.
- NEGATIVE FOR ACUTE APPENDICITIS.
- NEGATIVE FOR ACUTE PERIAPPENDICITIS.
</pre>
 
====Micro====
The sections show appendiceal wall with focal mucosa erosions and several intraluminal
neutrophil clusters.  Lymphoid hyperplasia is present. Fecal material is present within
the lumen of the appendix.
 
There are no neutrophils within the muscularis propria. There is no serositis. There is
no distortion of the crypt architecture. No granulomas are identified. No cryptitis is
identified.


=Inflammatory pathologies=
=Inflammatory pathologies=
==Acute appendicitis==
==Acute appendicitis==
===General===
{{Main|Acute appendicitis}}
*Bread 'n butter of general surgery.
*Interesting factoid: appendicitis is considered protective against [[ulcerative colitis]].<ref name=pmid19685454>{{Cite journal  | last1 = Beaugerie | first1 = L. | last2 = Sokol | first2 = H. | title = Appendicitis, not appendectomy, is protective against ulcerative colitis, both in the general population and first-degree relatives of patients with IBD. | journal = Inflamm Bowel Dis | volume =  | issue =  | pages =  | month = Aug | year = 2009 | doi = 10.1002/ibd.21064 | PMID = 19685454 }}</ref><ref name=pmid19273505>{{Cite journal  | last1 = Timmer | first1 = A. | last2 = Obermeier | first2 = F. | title = Reduced risk of ulcerative colitis after appendicectomy. | journal = BMJ | volume = 338 | issue =  | pages = b225 | month =  | year = 2009 | doi =  | PMID = 19273505 }}</ref>
 
Short clinical DDx:
*GI tract:
**Symptomatic [[Meckel diverticulum]].
**Epiploic appendagitis.
*Gynecologic tract:
**Ectopic pregnancy.
**Ruptured ovarian cyst.
**Ovarian torsion.
***Pelvic inflammatory disease.
 
===Gross===
Features:
*Serosal surface dull.
*May be perforated (best determined on gross).
*+/-Fibrinous exudate.
 
Note:
*Normal diameter of appendix (based on CT): 6.6 +/- 1.5 mm.<ref name=pmid21344807>{{Cite journal  | last1 = Charoensak | first1 = A. | last2 = Pongpornsup | first2 = S. | last3 = Suthikeeree | first3 = W. | title = Wall thickness and outer diameter of the normal appendix in adults using 64 slices multidetector CT. | journal = J Med Assoc Thai | volume = 93 | issue = 12 | pages = 1437-42 | month = Dec | year = 2010 | doi =  | PMID = 21344807 }}</ref>
**Similar numbers are found in another study.<ref name=pmid17457270>{{Cite journal  | last1 = Huwart | first1 = L. | last2 = El Khoury | first2 = M. | last3 = Lesavre | first3 = A. | last4 = Phan | first4 = C. | last5 = Rangheard | first5 = AS. | last6 = Bessoud | first6 = B. | last7 = Menu | first7 = Y. | title = [What is the thickness of the normal appendix on MDCT?]. | journal = J Radiol | volume = 88 | issue = 3 Pt 1 | pages = 385-9 | month = Mar | year = 2007 | doi =  | PMID = 17457270 }}</ref>
 
===Microscopic===
Features:
* Neutrophils in the muscularis propria - '''key feature'''.
* +/- Vascular [[thrombosis]] (and [[necrosis]]) - known as ''gangrenous appendicitis''.<ref>URL: [http://emedicine.medscape.com/article/363818-overview http://emedicine.medscape.com/article/363818-overview]. Accessed on: 21 June 2010.</ref>
* +/- Findings suggestive of etiology - usu. absent:
** +/- Fecalith.
** +/- Viral inclusions (extremely rare)
*** See ''[[adenovirus appendicitis]]''.
 
Note:
*Eosinophils are very common.<ref name=pmid9444860>{{Cite journal  | last1 = Aravindan | first1 = KP. | title = Eosinophils in acute appendicitis: possible significance. | journal = Indian J Pathol Microbiol | volume = 40 | issue = 4 | pages = 491-8 | month = Oct | year = 1997 | doi =  | PMID = 9444860 }}</ref>
**Appendices with eosinophils but no apparent [[neutrophil]]s probably represent the same process.<ref name=pmid20551528>{{Cite journal  | last1 = Aravindan | first1 = KP. | last2 = Vijayaraghavan | first2 = D. | last3 = Manipadam | first3 = MT. | title = Acute eosinophilic appendicitis and the significance of eosinophil - Edema lesion. | journal = Indian J Pathol Microbiol | volume = 53 | issue = 2 | pages = 258-61 | month =  | year =  | doi = 10.4103/0377-4929.64343 | PMID = 20551528 }}</ref>
 
DDx:
*Mucinous tumour.
*[[Neuroendocrine tumour]].
*[[Granulomatous appendicitis]].
*[[Crohn's disease]] of the appendix.
**Approximately of 40% colectomies for CD (that include an appendix) have involvement of the appendix.<ref name=pmid11956821>{{Cite journal  | last1 = Stangl | first1 = PC. | last2 = Herbst | first2 = F. | last3 = Birner | first3 = P. | last4 = Oberhuber | first4 = G. | title = Crohn's disease of the appendix. | journal = Virchows Arch | volume = 440 | issue = 4 | pages = 397-403 | month = Apr | year = 2002 | doi = 10.1007/s004280100532 | PMID = 11956821 }}</ref>
 
====Images====
<gallery>
Image:Appendicitis_-_low_mag.jpg | Appendicitis - low mag. (WC/Nephron)
Image:Appendicitis_-_very_high_mag.jpg | Appendicitis - very high mag. (WC/Nephron)
</gallery>
 
===Sign out===
<pre>
VERMIFORM APPENDIX, APPENDECTOMY:
- ACUTE APPENDICITIS.
- ACUTE PERIAPPENDICITIS.
</pre>
 
<pre>
VERMIFORM APPENDIX, APPENDECTOMY:
- GANGRENOUS APPENDICITIS.
- ACUTE PERIAPPENDICITIS.
</pre>
 
====Perforated appendicitis====
<pre>
VERMIFORM APPENDIX, APPENDECTOMY:
- ACUTE APPENDICITIS WITH PERFORATION AND ACUTE PERIAPPENDICITIS.
</pre>
 
This is uncommon to see definitively on histology.
====Micro====
=====Gangrenous appendicitis=====
The sections shows appendiceal wall with marked acute transmural inflammation and necrotic appendiceal wall with large collections of neutrophils.  Several medium-sized blood vessels are thrombosed.  A thick layer of neutrophils cover the serosa aspect.


==Adenovirus appendicitis==
==Adenovirus appendicitis==
===General===
{{Main|Adenovirus appendicitis}}
*Rare type of appendicitis in children.
*Presents as run-of-the-mill acute appendicitis.
*Caused by ''[[Adenovirus]]''.
 
===Microscopic===
Features:<ref name=pmid17990936>{{cite journal |author=Grynspan D, Rabah R |title=Adenoviral appendicitis presenting clinically as acute appendicitis |journal=Pediatr. Dev. Pathol. |volume=11 |issue=2 |pages=138–41 |year=2008 |pmid=17990936 |doi=10.2350/07-06-0299.1 |url=}}</ref>
*Lymphoid hyperplasia - key feature.
*+/-Adenovirus inclusions; "smudge cells".
 
Notes:
*The classic finding of appendicitis (neutrophils infiltrating into the muscularis propria) may be absent.<ref name=pmid17990936/>
 
Image:
*[http://wiki.medpedia.com/Image:Ab14.jpg?filetimestamp=20091014175858 Smudge cell (medpedia.com)].
 
===IHC===
*Adenovirus +ve = '''diagnostic'''.


==Enterobius vermicularis==
==Enterobius vermicularis==
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*May be found in the appendix.
*May be found in the appendix.
*The incidence is higher in normal appendices than inflamed ones.<ref name=pmid1853157>{{Cite journal  | last1 = Wiebe | first1 = BM. | title = Appendicitis and Enterobius vermicularis. | journal = Scand J Gastroenterol | volume = 26 | issue = 3 | pages = 336-8 | month = Mar | year = 1991 | doi =  | PMID = 1853157 }}</ref><ref name=pmid7945067/>
*The incidence is higher in normal appendices than inflamed ones.<ref name=pmid1853157>{{Cite journal  | last1 = Wiebe | first1 = BM. | title = Appendicitis and Enterobius vermicularis. | journal = Scand J Gastroenterol | volume = 26 | issue = 3 | pages = 336-8 | month = Mar | year = 1991 | doi =  | PMID = 1853157 }}</ref><ref name=pmid7945067/>
*Clinically mimics appendicitis.<ref>{{cite journal |author=Ariyarathenam AV, Nachimuthu S, Tang TY, Courtney ED, Harris SA, Harris AM |title=Enterobius vermicularis infestation of the appendix and management at the time of laparoscopic appendectomy: case series and literature review |journal=Int J Surg |volume=8 |issue=6 |pages=466–9 |year=2010 |pmid=20637320 |doi=10.1016/j.ijsu.2010.06.007 |url=}}</ref>


===Microscopic===
===Microscopic===
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==Granulomatous appendicitis==
==Granulomatous appendicitis==
===General===
{{Main|Granulomatous appendicitis}}
Most common cause:
*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>
 
DDx:<ref>[http://granuloma.homestead.com/appendicitis.html http://granuloma.homestead.com/appendicitis.html]</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>
**Yersinia = gram negative rod (red on [[Gram stain]]).
**"Safety pin"-like appearance<ref>URL: [http://www.cdc.gov/ncidod/dvbid/plague/p1.htm http://www.cdc.gov/ncidod/dvbid/plague/p1.htm]. Accessed on: 30 June 2011.</ref> - approximately 0.5 micrometers diameter x 2 micrometers length.
*Other micro-organism ([[TB]], fungus).
*[[Crohn's disease]].
*[[Sarcoidosis]].
*Foreign body reaction.
*Interval (delayed) appendectomy.
**Approximately 60% of delayed appendectomies have granulomas.<ref name=pmid12883248>{{Cite journal  | last1 = Guo | first1 = G. | last2 = Greenson | first2 = JK. | title = Histopathology of interval (delayed) appendectomy specimens: strong association with granulomatous and xanthogranulomatous appendicitis. | journal = Am J Surg Pathol | volume = 27 | issue = 8 | pages = 1147-51 | month = Aug | year = 2003 | doi =  | PMID = 12883248 }}</ref>
 
===Microscopic===
Features:
*[[Granulomas]].
*+/-"Safety pin"-like organisms (Yersinia).
 
Image(s):
*[http://www.cdc.gov/ncidod/dvbid/plague/p1.htm Yersinia (CDC)].


==Inflammatory bowel disease==
==Inflammatory bowel disease==
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*Acute inflammation of the serosa.
*Acute inflammation of the serosa.
**[[Neutrophil]]s in the serosa.
**[[Neutrophil]]s in the serosa.
DDx:
*[[Acute appendicitis]].


=Tumours of the appendix=
=Tumours of the appendix=
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==Mucinous tumours of the appendix==
==Mucinous tumours of the appendix==
:''Benign appendiceal [[mucocele]]'' and ''appendiceal mucocele'' redirect here.
{{Main|Mucinous tumours of the appendix}}
===General===
This grouping includes ''mucinous cystadenoma'' and ''mucinous cystadenocarcinoma''.
*There are many classifications and they are controversial.<ref name=pmid21970481>{{Cite journal  | last1 = Panarelli | first1 = NC. | last2 = Yantiss | first2 = RK. | title = Mucinous neoplasms of the appendix and peritoneum. | journal = Arch Pathol Lab Med | volume = 135 | issue = 10 | pages = 1261-8 | month = Oct | year = 2011 | doi = 10.5858/arpa.2011-0034-RA | PMID = 21970481 }}</ref>
**The controversy centres on whether to call all mucinous tumours outside of the appendix ''adenocarcinoma'' - regardless of whether they have atypia & show invasion.
*''Panarelli and Yantiss'' created a nice summary table - that compare the classifications - see: [http://www.archivesofpathology.org/action/showFullPopup?id=i1543-2165-135-10-1261-t01&doi=10.5858%2Farpa.2011-0034-RA comparison of classifications (archivesofpathology.org)].<ref name=pmid21970481/>
*In women - an ovarian primary must be excluded.
**Concurrent ''bilateral'' ovarian tumours suggests the tumour originated from the appendix and spread to the ovaries.
*[[Onlinepathology]] prefers the classification of Misdraji,<ref name=pmid12883241>{{cite journal |author=Misdraji J, Yantiss RK, Graeme-Cook FM, Balis UJ, Young RH |title=Appendiceal mucinous neoplasms: a clinicopathologic analysis of 107 cases |journal=Am. J. Surg. Pathol. |volume=27 |issue=8 |pages=1089–103 |year=2003 |month=August |pmid=12883241 |doi= |url=http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?issn=0147-5185&volume=27&issue=8&spage=1089}}</ref> as it is the least complicated
 
====Misdraji classification====
*Benign - ''low grade mucinous tumour''.
*Borderline - ''mucinous tumour of uncertain malignant potential'' or ''borderline mucinous tumour''.
*Malignant - ''[[mucinous adenocarcinoma]]''.
 
Five year survival (in a series of 107 cases) as per Misdraji classification:<ref name=pmid12883241/>
{| class="wikitable sortable"
!Tumour
!Five year survival
|-
|LAMN
|100%
|-
|LAMN extra-appendiceal spread
|86%
|-
|MACA
|44%
|-
|}
*LAMN = low-grade appendiceal mucinous neoplasm.
*LAMN extra-appendiceal = low-grade appendiceal mucinous neoplasm with extra-appendiceal spread.
*MACA = mucinous adenocarcinoma of the appendix.
 
====World Health Organization classification====
WHO classification:
*Adenoma with low-grade dysplasia.
*Adenoma with high-grade dysplasia.
*Low-grade invasive mucinous adenocarcinoma
**Confined to the appendiceal wall.
**Outside of the appendix.
*High-grade invasive mucinous adenocarcinoma.
 
====Comparison between Misdraji and WHO classification====
Adapted from ''Panarelli and Yantiss'':<ref name=pmid21970481>{{Cite journal  | last1 = Panarelli | first1 = NC. | last2 = Yantiss | first2 = RK. | title = Mucinous neoplasms of the appendix and peritoneum. | journal = Arch Pathol Lab Med | volume = 135 | issue = 10 | pages = 1261-8 | month = Oct | year = 2011 | doi = 10.5858/arpa.2011-0034-RA | PMID = 21970481 }}</ref>
{| class="wikitable sortable"
! Stage
! Cytologic dysplasia
! Misdraji
! World Health Organization
|-
| Confined to the mucosa
| low-grade
| low-grade appendiceal mucinous neoplasm (LAMN)
| mucinous adenoma, negative for high-grade dysplasia
|-
| Confined to the mucosa
| high-grade
| non-invasive mucinous cystadenocarcinoma of the appendix
| mucinous adenoma with high-grade dysplasia
|-
| At least into the submucosa, confined to the appendix
| low-grade
| low-grade appendiceal mucinous neoplasm (LAMN)
| invasive mucinous adenocarcinoma, low-grade
|-
| At least into the submucosa, confined to the appendix
| high-grade
| mucinous adenocarcinoma of the appendix (MACA)
| invasive mucinous adenocarcinoma, high-grade
|-
| Extra-appendiceal spread
| low-grade
| low-grade appendiceal mucinous neoplasm (LAMN)
| invasive mucinous adenocarcinoma, low-grade
|-
| Extra-appendiceal spread
| high-grade
| mucinous adenocarcinoma of the appendix (MACA)
| invasive mucinous adenocarcinoma, high-grade
|}
 
===Microscopic===
====Low-grade appendiceal mucinous neoplasm====
*[[AKA]] ''benign mucinous tumour of the appendix''.
 
Microscopic:
*Single layer of epithelium with ''tufts''.
**Vaguely resemble ''serrations'', i.e. the ''saw-tooth'' pattern in hyperplastic polyps of the colon.
*Mucin contained (inside appendix only).
*No marked nuclear atypia.
 
Note:
*May be deceptively bland appearing from a cytologic perspective.
 
Images:
*[http://www.nature.com/modpathol/journal/v17/n12/fig_tab/3800212f1.html LAMN - low mag. (nature.com)].<ref name=pmid15354187/>
*[http://www.nature.com/modpathol/journal/v17/n12/fig_tab/3800212f3.html LAMN - high mag. (nature.com)].<ref name=pmid15354187>{{Cite journal  | last1 = Misdraji | first1 = J. | last2 = Burgart | first2 = LJ. | last3 = Lauwers | first3 = GY. | title = Defective mismatch repair in the pathogenesis of low-grade appendiceal mucinous neoplasms and adenocarcinomas. | journal = Mod Pathol | volume = 17 | issue = 12 | pages = 1447-54 | month = Dec | year = 2004 | doi = 10.1038/modpathol.3800212 | PMID = 15354187 }}</ref>
*[http://pathlabmed.typepad.com/surgical_pathology_and_la/2012/02/digital-case-simple-mucocele-of-the-appendix.html Appendiceal mucocele (pathlabmed.typepad.com)].
 
====Low-grade appendiceal mucinous neoplasm with extra-appendiceal spread====
*[[AKA]] ''mucinous borderline tumour of the appendix''.
 
Microscopic:
*Same as LAMN but mucin outside of the appendix.
*Cells in mucin, i.e. cellular mucin.
 
====Mucinous adenocarcinoma of the appendix====
*[[AKA]] ''malignant mucinous tumour of the appendix''.
 
Microscopic:
*Marked nuclear pleomorphism.
*Invasion into the appendiceal wall.
 
===Sign out===
====LAMN====
<pre>
VERMIFORM APPENDIX, APPENDECTOMY:
- LOW-GRADE APPENDICEAL MUCINOUS NEOPLASM.
- ACUTE APPENDICITIS.
- ACUTE PERIAPPENDICITIS.
</pre>
 
<pre>
VERMIFORM APPENDIX AND CECUM, APPENDECTOMY WITH CECAL CUFF:
- LOW-GRADE APPENDICEAL MUCINOUS NEOPLASM (MUCINOUS CYSTADENOMA).
- MARGINS NEGATIVE FOR MUCINOUS NEOPLASM.
 
COMMENT:
No extra-appendiceal mucin is identified. There is no invasion into the appendiceal wall.
</pre>
 
==Goblet cell carcinoid==
*[[AKA]] ''crypt cell carcinoma''.<ref name=pmid18042066>{{cite journal |author=van Eeden S, Offerhaus GJ, Hart AA, ''et al.'' |title=Goblet cell carcinoid of the appendix: a specific type of carcinoma |journal=Histopathology |volume=51 |issue=6 |pages=763–73 |year=2007 |month=December |pmid=18042066 |doi=10.1111/j.1365-2559.2007.02883.x |url=}}</ref>
*[[AKA]] ''[[neuroendocrine tumour]] with goblet cell differentiation''.
===General===
*Rare appendiceal tumour that typically has an aggressive course vis-a-vis other appendiceal carcinoids.<ref name=pmid18042066>{{cite journal |author=van Eeden S, Offerhaus GJ, Hart AA, ''et al.'' |title=Goblet cell carcinoid of the appendix: a specific type of carcinoma |journal=Histopathology |volume=51 |issue=6 |pages=763–73 |year=2007 |month=December |pmid=18042066 |doi=10.1111/j.1365-2559.2007.02883.x |url=}}</ref>
*Mixed (biphasic) tumour with endocrine and exocrine features.
 
===Microscopic===
Features:<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>
*Mixed neuroendocrine-nonneuroendocrine tumour;<ref name=pmid17684764>{{cite journal |author=Volante M, Righi L, Asioli S, Bussolati G, Papotti M |title=Goblet cell carcinoids and other mixed neuroendocrine/nonneuroendocrine neoplasms |journal=Virchows Arch. |volume=451 Suppl 1 |issue= |pages=S61–9 |year=2007 |month=August |pmid=17684764 |doi=10.1007/s00428-007-0447-y |url=}}</ref> features of both ''carcinoid'' and ''adenocarcinoma.<ref name=pmid15967038>PMID 15967038.</ref>
**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.
 
====Images====
<gallery>
Image:Goblet_cell_carcinoid_-2-_very_high_mag.jpg | GCC - very high mag. (WC/Nephron)
Image:Goblet_cell_carcinoid_-_very_low_mag.jpg | GCC - very low mag. (WC/Nephron)
</gallery>
 
===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:
==Goblet cell adenocarcinoma==
*Usually CK20 +ve > CK7 +ve.
{{Main|Goblet cell adenocarcinoma}}
 
*Previously known as ''goblet cell carcinoid''.
*CEA +ve (membrane).
 
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>


==Neuroendocrine tumour of the appendix==
==Neuroendocrine tumour of the appendix==
{{Main|Neuroendocrine tumour}}
*Previously known as ''appendiceal carcinoid''.
*Previously known as ''appendiceal carcinoid''.
*[[AKA]] ''appendiceal neuroendocrine tumour'', abbreviated ''appendiceal NET''.  
*[[AKA]] ''appendiceal neuroendocrine tumour'', abbreviated ''appendiceal NET''.  
===General===
{{Main|Neuroendocrine tumour of the appendix}}
*Most common tumour of the appendix.<ref name=PCPBoD8_435>{{Ref PCPBoD8|435}}</ref>
 
Size matters in ''appendiceal NETs'':<ref name=pmid12569593>{{Cite journal  | last1 = Modlin | first1 = IM. | last2 = Lye | first2 = KD. | last3 = Kidd | first3 = M. | title = A 5-decade analysis of 13,715 carcinoid tumors. | journal = Cancer | volume = 97 | issue = 4 | pages = 934-59 | month = Feb | year = 2003 | doi = 10.1002/cncr.11105 | PMID = 12569593 }}</ref>
*<1.0 cm - do not metastasize.
*1.0-2.0 cm - rarely metastasize.
 
===Microscopic===
Features:
*See ''[[neuroendocrine tumours]]''.
 
===IHC===
Features:
*Chromogranin A -ve/+ve.
*Synaptophysin +ve.
 
See: ''[[neuroendocrine tumours]]''.


=See also=
=See also=
Line 443: Line 123:


[[Category:Gastrointestinal pathology]]
[[Category:Gastrointestinal pathology]]
[[Category:Vermiform appendix]]

Latest revision as of 15:11, 4 December 2023

The vermiform appendix, usually just appendix, is a little thingy that is attached to the cecum. 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]

Normal

Normal vermiform appendix

General

Gross

  • Shiny serosal surface.
    • No exudate.
  • Normal diameter.
    • 6.6 +/- 1.5 mm -- based on CT.[2]

Microscopic

Features:

  • +/-Lymphoid hyperplasia - mucosa or submucosa.
  • Normal colorectal-type mucosa.
  • Fatty submucosa.
  • Benign smooth muscle.
  • Serosa.

Negatives:

DDx:

Sign out

VERMIFORM APPENDIX WITHIN NORMAL LIMITS.

Note:

  • This is for a normal appendix within a larger operation. The article negative appendectomy deals with a normal appearing appendix that was removed for presumed appendicitis.

Negative appendectomy

Main article: Negative appendectomy

An appendectomy done for presumed acute appendicitis that is pathologically within normal limits

Inflammatory pathologies

Acute appendicitis

Main article: Acute appendicitis

Adenovirus appendicitis

Main article: Adenovirus appendicitis

Enterobius vermicularis

Main article: Enterobius vermicularis

General

  • May be found in the appendix.
  • The incidence is higher in normal appendices than inflamed ones.[3][4]
  • Clinically mimics appendicitis.[5]

Microscopic

Features:

Image

  • Enterobius - very low mag. (WC/Nephron)

  • Enterobius - high mag. (WC/Nephron)

  • Pinworm (WC/Uthman)

Granulomatous appendicitis

Main article: Granulomatous appendicitis

Inflammatory bowel disease

See Inflammatory bowel disease.

Periappendicitis

General

Definition: inflammation of tissues around the (vermiform) appendix.[6]

  • May be seen in association of appendicitis or alone.
    • With appendicitis it is suggestive of perforation.
    • Without concurrent appendicitis it is suggestive of another abdominal pathology.[7][8]

Microscopic

Features:

  • Acute inflammation of the serosa.

DDx:

Tumours of the appendix

Adenocarcinoma

Mucinous tumours of the appendix

Main article: Mucinous tumours of the appendix

This grouping includes mucinous cystadenoma and mucinous cystadenocarcinoma.

Goblet cell adenocarcinoma

Main article: Goblet cell adenocarcinoma
  • Previously known as goblet cell carcinoid.

Neuroendocrine tumour of the appendix

  • Previously known as appendiceal carcinoid.
  • AKA appendiceal neuroendocrine tumour, abbreviated appendiceal NET.
Main article: Neuroendocrine tumour of the appendix

See also

References

  1. ↑ Dawkins, R. (2009). The Greatest Show on Earth: The Evidence for Evolution (1st ed.). Free Press. pp. 115. ISBN 978-1416594789.
  2. ↑ Charoensak, A.; Pongpornsup, S.; Suthikeeree, W. (Dec 2010). "Wall thickness and outer diameter of the normal appendix in adults using 64 slices multidetector CT.". J Med Assoc Thai 93 (12): 1437-42. PMID 21344807.
  3. ↑ 3.0 3.1 Wiebe, BM. (Mar 1991). "Appendicitis and Enterobius vermicularis.". Scand J Gastroenterol 26 (3): 336-8. PMID 1853157.
  4. ↑ 4.0 4.1 Dahlstrom, JE.; Macarthur, EB. (Oct 1994). "Enterobius vermicularis: a possible cause of symptoms resembling appendicitis.". Aust N Z J Surg 64 (10): 692-4. PMID 7945067.
  5. ↑ Ariyarathenam AV, Nachimuthu S, Tang TY, Courtney ED, Harris SA, Harris AM (2010). "Enterobius vermicularis infestation of the appendix and management at the time of laparoscopic appendectomy: case series and literature review". Int J Surg 8 (6): 466–9. doi:10.1016/j.ijsu.2010.06.007. PMID 20637320.
  6. ↑ URL: http://www.medilexicon.com/medicaldictionary.php?t=66889. Accessed on: 1 June 2011.
  7. ↑ Fink, AS.; Kosakowski, CA.; Hiatt, JR.; Cochran, AJ. (Jun 1990). "Periappendicitis is a significant clinical finding.". Am J Surg 159 (6): 564-8. PMID 2349982.
  8. ↑ O'Neil, MB.; Moore, DB. (Sep 1977). "Periappendicitis: Clinical reality or pathologic curiosity?". Am J Surg 134 (3): 356-7. PMID 900337.
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