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Mucinous tumours of the appendix (view source)

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#redirect [[Vermiform_appendix#Mucinous_tumours_of_the_appendix]]
{{ Infobox external links
| Name          = Mucinous tumours of the appendix
| EHVSC          = 10183
| pathprotocols  =
| wikipedia      =
| pathoutlines  =
}}
'''Mucinous tumours of the appendix''' are uncommon tumours of the [[vermiform appendix]] that can have a benign or [[malignant]] behaviour.
 
'''Benign appendiceal [[mucocele]]''' and '''appendiceal mucocele''' redirect here.
==General==
*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>
 
<pre>
APPENDIX, APPENDECTOMY:
- APPENDICEAL MUCINOUS CYSTADENOMA WITH EXTENSIVE CALCIFICATION.
-- NEGATIVE FOR HIGH-GRADE DYSPLASIA.
- NEGATIVE FOR MALIGNANCY.
</pre>
 
==See also==
*[[Vermiform appendix]].
*[[Mucinous carcinoma]].
 
==References==
{{Reflist|2}}
 
[[Category:Vermiform appendix]]
Michael
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