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'''Colorectal tumours''', especially '''colorectal carcinomas''', are very common. They are the bread and butter of GI pathology. Non-tumour colon is dealt with in the ''[[colon]]'' article. | '''Colorectal tumours''', especially '''colorectal carcinomas''', are very common. They are the bread and butter of GI pathology. Non-tumour colon is dealt with in the ''[[colon]]'' article. | ||
''Colonic tumours'' and ''rectal tumours'' redirect here. | |||
An introduction to gastrointestinal pathology is in the ''[[gastrointestinal pathology]]'' article. The precursor lesion of colorectal carcinoma (CRC) is, typically, an [[adenomatous polyps|adenomatous polyp]]. Polyps are discussed in the ''[[intestinal polyps]]'' article. | An introduction to gastrointestinal pathology is in the ''[[gastrointestinal pathology]]'' article. The precursor lesion of colorectal carcinoma (CRC) is, typically, an [[adenomatous polyps|adenomatous polyp]]. Polyps are discussed in the ''[[intestinal polyps]]'' article. | ||
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=Classification= | =Classification= | ||
===Most common=== | ===Most common=== | ||
*Colon & rectum - most common = [[adenocarcinoma]].<ref name=Ref_PBoD864>{{Ref PBoD|864}}</ref> | *Colon & rectum - most common = [[colorectal adenocarcinoma|adenocarinoma]].<ref name=Ref_PBoD864>{{Ref PBoD|864}}</ref> | ||
===Others=== | ===Others=== | ||
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*[[Mucinous carcinoma]]. | *[[Mucinous carcinoma]]. | ||
**Need > 50% mucinous component.<ref name=pmid17679024 >{{cite journal |author=Tozawa E, Ajioka Y, Watanabe H, ''et al.'' |title=Mucin expression, p53 overexpression, and peritumoral lymphocytic infiltration of advanced colorectal carcinoma with mucus component: is mucinous carcinoma a distinct histological entity? |journal=Pathol. Res. Pract. |volume=203 |issue=8 |pages=567–74 |year=2007 |pmid=17679024 |doi=10.1016/j.prp.2007.04.013 |url=}}</ref> | **Need > 50% mucinous component.<ref name=pmid17679024 >{{cite journal |author=Tozawa E, Ajioka Y, Watanabe H, ''et al.'' |title=Mucin expression, p53 overexpression, and peritumoral lymphocytic infiltration of advanced colorectal carcinoma with mucus component: is mucinous carcinoma a distinct histological entity? |journal=Pathol. Res. Pract. |volume=203 |issue=8 |pages=567–74 |year=2007 |pmid=17679024 |doi=10.1016/j.prp.2007.04.013 |url=}}</ref> | ||
*Adenosquamous carcinoma. | *[[Adenosquamous carcinoma]]. | ||
*Signet-ring carcinoma. | *Signet-ring carcinoma. | ||
*Squamous carcinoma. | *Squamous carcinoma. | ||
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*Rare. | *Rare. | ||
**In the context of a rectal tumour, retrograde growth from the [[anus]] should be considered. | **In the context of a rectal tumour, retrograde growth from the [[anus]] should be considered. | ||
==Staging of colorectal cancer== | ==Staging of colorectal cancer== | ||
{{Main|Colorectal cancer staging}} | |||
==Pathogenesis of colorectal carcinoma== | |||
==Pathogenesis== | |||
===Overview=== | ===Overview=== | ||
Colorectal carcinoma is thought to arise from one of two pathways:<ref name=pmid16483003>{{cite journal |author=Goldstein NS |title=Serrated pathway and APC (conventional)-type colorectal polyps: molecular-morphologic correlations, genetic pathways, and implications for classification |journal=Am. J. Clin. Pathol. |volume=125 |issue=1 |pages=146–53 |year=2006 |month=January |pmid=16483003 |doi= |url=}}</ref><ref name=pmid18314605>{{cite journal |author=Rüschoff J, Aust D, Hartmann A |title=[Colorectal serrated adenoma: diagnostic criteria and clinical implications] |language=German |journal=Verh Dtsch Ges Pathol |volume=91 |issue= |pages=119–25 |year=2007 |pmid=18314605 |doi= |url=}}</ref> | Colorectal carcinoma is thought to arise from one of two pathways:<ref name=pmid16483003>{{cite journal |author=Goldstein NS |title=Serrated pathway and APC (conventional)-type colorectal polyps: molecular-morphologic correlations, genetic pathways, and implications for classification |journal=Am. J. Clin. Pathol. |volume=125 |issue=1 |pages=146–53 |year=2006 |month=January |pmid=16483003 |doi= |url=}}</ref><ref name=pmid18314605>{{cite journal |author=Rüschoff J, Aust D, Hartmann A |title=[Colorectal serrated adenoma: diagnostic criteria and clinical implications] |language=German |journal=Verh Dtsch Ges Pathol |volume=91 |issue= |pages=119–25 |year=2007 |pmid=18314605 |doi= |url=}}</ref> | ||
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====Syndromes==== | ====Syndromes==== | ||
Both of the above described pathways are associated with syndromes: | Both of the above described pathways are associated with syndromes: | ||
#''[[Familial adenomatous polyposis]]'' (FAP) or ''familial polyposis coli'' (FPC). | |||
#''Lynch syndrome'' ([[AKA]] ''[[hereditary non-polyposis colorectal cancer syndrome]]'' (HNPCC)). | |||
===Pathways=== | ===Pathways=== | ||
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====Mismatch repair pathway==== | ====Mismatch repair pathway==== | ||
*Associated with microsatellite instability (MSI | *Associated with [[microsatellite instability]] (MSI). | ||
===Other ancillary studies=== | ===Other ancillary studies=== | ||
*BRAF ''V600E'' missense mutation found in ~10% CRC.<ref name=pmid20635392>{{cite journal |author=Tie J, Gibbs P, Lipton L, ''et al.'' |title=Optimizing targeted therapeutic development: Analysis of a colorectal cancer patient population with the BRAF(V600E) mutation |journal=Int J Cancer |volume= |issue= |pages= |year=2010 |month=July |pmid=20635392 |doi=10.1002/ijc.25555 |url=}}</ref> | *BRAF ''V600E'' missense mutation found in ~10% CRC.<ref name=pmid20635392>{{cite journal |author=Tie J, Gibbs P, Lipton L, ''et al.'' |title=Optimizing targeted therapeutic development: Analysis of a colorectal cancer patient population with the BRAF(V600E) mutation |journal=Int J Cancer |volume= |issue= |pages= |year=2010 |month=July |pmid=20635392 |doi=10.1002/ijc.25555 |url=}}</ref> | ||
*KRAS mutation status. | *[[KRAS mutation]] status. | ||
====BRAF V600E mutation==== | ====BRAF V600E mutation==== | ||
{{Main|BRAF V600E mutation}} | |||
Features:<ref name=pmid20635392/> | Features:<ref name=pmid20635392/> | ||
*Independently associated with BRAF V600E: | *Independently associated with BRAF V600E: | ||
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====KRAS mutation==== | ====KRAS mutation==== | ||
{{Main|KRAS mutation}} | |||
Features:<ref name=pmid20956938>{{cite journal |author=Dunn EF, Iida M, Myers RA, ''et al.'' |title=Dasatinib sensitizes KRAS mutant colorectal tumors to cetuximab |journal=Oncogene |volume= |issue= |pages= |year=2010 |month=October |pmid=20956938 |doi=10.1038/onc.2010.430 |url=}}</ref><ref name=pmid19001320>{{cite journal |author=Di Nicolantonio F, Martini M, Molinari F, ''et al.'' |title=Wild-type BRAF is required for response to panitumumab or cetuximab in metastatic colorectal cancer |journal=J. Clin. Oncol. |volume=26 |issue=35 |pages=5705–12 |year=2008 |month=December |pmid=19001320 |doi=10.1200/JCO.2008.18.0786 |url=}}</ref> | Features:<ref name=pmid20956938>{{cite journal |author=Dunn EF, Iida M, Myers RA, ''et al.'' |title=Dasatinib sensitizes KRAS mutant colorectal tumors to cetuximab |journal=Oncogene |volume= |issue= |pages= |year=2010 |month=October |pmid=20956938 |doi=10.1038/onc.2010.430 |url=}}</ref><ref name=pmid19001320>{{cite journal |author=Di Nicolantonio F, Martini M, Molinari F, ''et al.'' |title=Wild-type BRAF is required for response to panitumumab or cetuximab in metastatic colorectal cancer |journal=J. Clin. Oncol. |volume=26 |issue=35 |pages=5705–12 |year=2008 |month=December |pmid=19001320 |doi=10.1200/JCO.2008.18.0786 |url=}}</ref> | ||
*Patient must have ''wild type'' KRAS to get drugs; KRAS mutation predicts resistance to [[cetuximab]] (Erbitux) and [[panitumumab]] (Vectibix). | *Patient must have ''wild type'' KRAS to get drugs; KRAS mutation predicts resistance to [[cetuximab]] (Erbitux) and [[panitumumab]] (Vectibix). | ||
**Cetuximab and panitumumab are [[EGFR inhibitors]]. | **Cetuximab and panitumumab are [[EGFR inhibitors]]. | ||
== | ==Microsatellite instability cancers== | ||
* | *Abbreviated ''MSI cancers''. | ||
{{Main|Microsatellite instability in colorectal cancer}} | |||
=Specific entities= | =Specific entities= | ||
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*[[AKA]] ''colorectal adenocarcinoma not otherwise specified''. | *[[AKA]] ''colorectal adenocarcinoma not otherwise specified''. | ||
*[[AKA]] ''colorectal carcinoma'', abbreviated ''CRC''. | *[[AKA]] ''colorectal carcinoma'', abbreviated ''CRC''. | ||
{{Main|Colorectal adenocarcinoma}} | |||
==Secondary colorectal cancer== | |||
===General=== | ===General=== | ||
* | *Uncommon. | ||
* | *May be suspected. | ||
===Microscopic=== | ===Microscopic=== | ||
Features: | Features: | ||
* | *Normal colorectal mucosa. | ||
*Atypical cells in the lamina propria or submucosa. | |||
* | |||
DDx: | |||
* | *Colorectal neuroendocrine tumour. | ||
=== | ===Images=== | ||
<gallery> | |||
Image:Prostate carcinoma in rectum -- very low mag.jpg | Pca in rectum - very low mag. (WC) | |||
Image:Prostate carcinoma in rectum -- low mag.jpg | Pca in rectum - low mag. (WC) | |||
Image:Prostate carcinoma in rectum -- intermed mag.jpg | Pca in rectum - intermed. mag. (WC) | |||
Image:Prostate carcinoma in rectum -- high mag.jpg | Pca in rectum - high mag. (WC) | |||
</gallery> | |||
<gallery> | |||
Image:Prostate carcinoma in rectum - PSAP -- intermed mag.jpg | Pca in rectum - PSAP - intermed. mag. (WC) | |||
Image:Prostate carcinoma in rectum - PSA -- intermed mag.jpg | Pca in rectum - PSA - intermed. mag. (WC) | |||
Image:Prostate carcinoma in rectum - CK20 -- intermed mag.jpg | Pca in rectum - CK20 - intermed. mag. (WC) | |||
</gallery> | |||
=See also= | =See also= | ||
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*[[Colon]]. | *[[Colon]]. | ||
*[[Gastrointestinal pathology]]. | *[[Gastrointestinal pathology]]. | ||
*[[Tumour budding]]. | |||
*[[Tumour perforation in colorectal cancer]]. | |||
*[[Transanal minimally invasive surgery]]. | |||
=References= | =References= |
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