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Difference between revisions of "Vermiform appendix"
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→Neuroendocrine tumour of the appendix
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*Most common tumour of the appendix.<ref name=PCPBoD8_435>{{Ref PCPBoD8|435}}</ref> | *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> | **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> | 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> | ||
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===Gross=== | ===Gross=== | ||
*Classically found in the tip of the appendix. | *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: | Image: | ||
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===Microscopic=== | ===Microscopic=== | ||
Features: | Features: | ||
*Classically subepithelial/mural. | *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: | DDx: | ||
*[[Colorectal adenocarcinoma]]. | *[[Colorectal adenocarcinoma]]. | ||
*Adenocarcinoid. | |||
*[[Crypt cell carcinoma]] (goblet cell carcinoid). | *[[Crypt cell carcinoma]] (goblet cell carcinoid). | ||
*Metastatic adenocarcinoma. | *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==== | ====Images==== | ||
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*Chromogranin A -ve/+ve. | *Chromogranin A -ve/+ve. | ||
*Synaptophysin +ve. | *Synaptophysin +ve. | ||
*Keratin positive, but CK7/CK20 negative | |||
*S100 positive for appendix | |||
See: ''[[neuroendocrine tumours]]''. | See: ''[[neuroendocrine tumours]]''. | ||