Difference between revisions of "Vermiform appendix"

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Vermiform appendix (view source)

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→‎Neuroendocrine tumour of the appendix
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==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>
**Not really common though - one is seen in approximately 300 appendectomies.<ref name=pmid23416502>{{Cite journal  | last1 = Mitra | first1 = B. | last2 = Pal | first2 = M. | last3 = Paul | first3 = B. | last4 = Saha | first4 = TN. | last5 = Maiti | first5 = A. | title = Goblet cell carcinoid of appendix: A rare case with literature review. | journal = Int J Surg Case Rep | volume = 4 | issue = 3 | pages = 334-7 | month =  | year = 2013 | doi = 10.1016/j.ijscr.2013.01.007 | PMID = 23416502 }}</ref>
===Presentation===
** Often found incidentally, may be microscopic. 
** May cause obstruction leading to mucocele or acute appendicitis.
** May precipitate torsion.
 
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.
 
===Gross===
*Classically found in the tip of the appendix.
*Characteristic yellow cut surface (when fixed)
*Circumscribed but not encapsulated
*Firm (due to desmoplasia)
*Centred in the submucosa
*Nodules that do not usually cause erosion of the overlying mucosa.
 
 
Image:
<gallery>
Image:Appendiceal_carcinoid_1.JPG | Appendiceal neuroendocrine tumour. (WC)
</gallery>
 
===Microscopic===
Features:
*Classically subepithelial/mural.
*Various growth patterns:
**Nested (insular)
**Trabecular
**Palisading
**Ribbons, rosettes
*Fibrous stroma in between cell groups.
*Cytomorphology
**Monotonous appearance with scanty mitoses.
**Round central nuclei
**Stippled chromatin [[AKA]] salt-and-pepper chromatin, coarse chromatin.
**Eosinophilic granular cytoplasm
 
===Special Types===
*Tubular carcinoid
**Neuroendocrine cells forming tubules (no cell nests)
**Some tubules can contain mucin
**Can be confused with adenocarcinoma
**Features suggesting tubular carcinoid (over adenocarcinoma):
***Arises from base of crypts, with no disruption of surface epithelium.
***No associated epithelial precursor (no adenomatous change).
***Neuroendocrine cytologic features, without prominent atypia
***IHC (NE markers +ve)
 
*Goblet cell carcinoid aka [[Crypt cell carcinoma]]
*Signet-ring cells forming glandular structures,
*Possibly also with extra-cellular mucin
 
DDx:
*[[Colorectal adenocarcinoma]].
*Adenocarcinoid.
*[[Crypt cell carcinoma]] (goblet cell carcinoid).
*Metastatic adenocarcinoma.
*Normal ganglion cells in the Meissner plexus (submucosa) and Auerbach plexus (located between the inner and outer layers of the muscularis propria).
 
====Images====
<gallery>
Image: Appendix Carcinoid Torsion 1X PA.JPG|Appendiceal carcinoid with torsion of the appendix - 1x (SKB)
Image: Appendix Carcinoid Torsion LP PA.JPG|Appendiceal carcinoid with torsion of the appendix - low power (SKB)
Image: Appendix Carcinoid Torsion MP PA.JPG|Appendiceal carcinoid with torsion of the appendix - medium power (SKB)
Image: Appendix Carcinoid LP 14BR***.jpg|Appendiceal carcinoid - low power (SKB)
Image: Appendix Carcinoid HP 14BR***.jpg|Appendiceal carcinoid  - high power (SKB)
Image: Appendix Carcinoid Synaptophysin 14BR17120.jpg|Appendiceal carcinoid -  synaptophysin (SKB)
Image: Appendix Carcinoid LP CTR.jpg|Appendiceal carcinoid  - low power (SKB)
Image: Appendix Carcinoid HP CTR.jpg|Appendiceal carcinoid - high power (SKB)
Image: Appendix Carcinoid LP PA.JPG|Appendiceal carcinoid - low power (SKB)
Image: Appendix Carcinoid Necrosis PA.JPG|Appendiceal carcinoid with necrosis (SKB)
</gallery>
www:
*[http://www.humpath.com/spip.php?article10881&id_document=19109#documents_portfolio Appendiceal carcinoid (humpath.com)].
*[http://www.brown.edu/Courses/Digital_Path/systemic_path/GI/AppendicealCarcinoid.html Carcinoid of the appendix (brown.edu)].
*[http://www.flickr.com/photos/jian-hua_qiao_md/8494061964/in/photostream/ Appendiceal carcinoid (flickr.com/Qiao)].
 
===IHC===
Features:
*Chromogranin A -ve/+ve.
*Synaptophysin +ve.
*Keratin positive, but CK7/CK20 negative
*S100 positive for appendix
 
See: ''[[neuroendocrine tumours]]''.


=See also=
=See also=
Michael
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