{{Infobox medical condition (new) | name = Colorectal adenoma | image = Tubulovillous adenoma.jpg | caption = ''Tubulovillous adenoma'' (tubular component – left of image, villous component – right of image). H&E stain. | pronounce = | field = Gastroenterology | synonyms = | symptoms = Asymptomatic, rectal bleeding | complications = Colorectal cancer | onset = | duration = | types = | causes = | risks = | diagnosis = Colonoscopy | differential = | prevention = | treatment = Polypectomy | medication = | prognosis = | frequency = | deaths = }} The '''colorectal adenoma''' is a benign glandular tumor of the colon and the rectum. It is a precursor lesion of the colorectal adenocarcinoma (colon cancer).<ref>{{Cite journal | pmid = 6384511 | year = 1984| last1 = Hardcastle| first1 = J. D.| title = Early diagnosis of colorectal cancer: A review| journal = Journal of the Royal Society of Medicine| volume = 77| issue = 8| pages = 673–6| last2 = Armitage| first2 = N. C.| doi = 10.1177/014107688407700812| pmc = 1440108}}</ref><ref>{{Cite journal | pmid = 1319254| year = 1992| last1 = Schofield| first1 = P. F.| title = ABC of colorectal diseases. Colorectal neoplasia—I: Benign colonic tumours| journal = BMJ (Clinical Research Ed.)| volume = 304| issue = 6840| pages = 1498–500| last2 = Jones| first2 = D. J.| pmc = 1882234 | doi=10.1136/bmj.304.6840.1498 }}</ref><ref>{{Cite journal | pmid = 11350874| year = 2001| last1 = Srivastava| first1 = S| title = Biomarkers for early detection of colon cancer| journal = Clinical Cancer Research| volume = 7 | issue = 5| pages = 1118–26| last2 = Verma| first2 = M| last3 = Henson| first3 = D. E.}}</ref> They often manifest as colorectal polyps.

==Comparison table== thumb|250px|Incidences and malignancy risks of various types of colorectal polyps. Adenomatous types are grouped at top. {|class="wikitable" |+ Colorectal adenoma ! Type !! Risk of containing malignant cells !! Histopathology definition |- ! Tubular adenoma | '''2%''' at 1.5&nbsp;cm<ref>{{cite web|url=https://www.msdmanuals.com/professional/gastrointestinal-disorders/tumors-of-the-gastrointestinal-tract/polyps-of-the-colon-and-rectum|title=Polyps of the Colon and Rectum|author=Minhhuyen Nguyen|website=MSD Manual}} Last full review/revision June 2019</ref> || Over 75% of volume has tubular appearance.<ref name=WHO>{{cite book | last=Bosman | first=F. T. | title=WHO classification of tumours of the digestive system | publisher=International Agency for Research on Cancer | publication-place=Lyon | year=2010 | isbn=978-92-832-2432-7 | oclc=688585784 }}</ref> |- ! Tubulovillous adenoma | '''20%''' to '''25%'''<ref name="AmersiAgustin2005">{{cite journal|last1=Amersi|first1=Farin|last2=Agustin|first2=Michelle|last3=Ko|first3=Clifford Y|title=Colorectal Cancer: Epidemiology, Risk Factors, and Health Services|journal=Clinics in Colon and Rectal Surgery|volume=18|issue=3|year=2005|pages=133–140|issn=1531-0043|doi=10.1055/s-2005-916274|pmid=20011296|pmc=2780097}}</ref> | 25–75% villous<ref name=WHO/> |- ! Villous adenoma | '''15%'''<ref name=Ramji2016>{{cite web|url=https://emedicine.medscape.com/article/170283-followup#e3|title=Villous Adenoma Follow-up|website=Medscape|author=Alnoor Ramji}} Updated: Oct 24, 2016</ref> to '''40%'''<ref name="AmersiAgustin2005"/> | Over 75% villous<ref name=WHO/> |- ! Sessile serrated adenoma (SSA)<ref>{{Cite journal | pmid = 23208018 | year = 2013 | last1 = Rosty | first1 = C | title = Serrated polyps of the large intestine: Current understanding of diagnosis, pathogenesis, and clinical management | journal = Journal of Gastroenterology | volume = 48 | issue = 3 | pages = 287–302 | last2 = Hewett | first2 = D. G. | last3 = Brown | first3 = I. S. | last4 = Leggett | first4 = B. A. | last5 = Whitehall | first5 = V. L. | doi = 10.1007/s00535-012-0720-y | pmc = 3698429 }}</ref> | | *Basal dilation of the crypts *Basal crypt serration *Crypts that run horizontal to the basement membrane (horizontal crypts) *Crypt branching. |}

==Tubular adenoma== In contrast to hyperplastic polyps, these display dysplasia.{{citation needed|date=August 2020}}

==Tubulovillous adenoma== ''Tubulovillous adenoma'', ''TVA'' are considered to have a higher risk of becoming malignant (cancerous) than tubular adenomas.<ref name=pmid17167138>{{Cite journal|vauthors=Levine JS, Ahnen DJ |title=Clinical practice. Adenomatous polyps of the colon |journal=N. Engl. J. Med. |volume=355 |issue=24 |pages=2551–7 |date=December 2006 |pmid=17167138 |doi=10.1056/NEJMcp063038 }}</ref> <gallery> File:Non-proliferative versus proliferative colonic crypts.jpg|Normal (left) versus dysplastic (large at right) colonic crypts, the latter conferring a diagnosis of a tubular and/or villous adenoma. File:Histopathology of high-grade dysplasia in tubulovillous adenoma, annotated.png|Histopathology of '''high-grade dysplasia''' in a tubulovillous adenoma, in this case seen mainly as loss of cell polarity, as cells become more plump and haphazard than the elongated and parallel nuclei of surrounding low-grade dysplasia. </gallery> ==Villous adenoma== [[File:Villous adenoma1.jpg|thumb|Micrograph of a colorectal villous adenoma. H&E stain]] These adenomas may become malignant (cancerous). Villous adenomas have been demonstrated to contain malignant portions in about 15–25% of cases, approaching 40% in those over 4&nbsp;cm in diameter.<ref name=Ramji2016/> Colonic resection may be required for large lesions. These can also lead to secretory diarrhea with large volume liquid stools with few formed elements. They are commonly described as secreting large amounts of mucus, resulting in hypokalaemia in patients. On endoscopy, a "cauliflower' like mass is described due to villi stretching. Being an adenoma, the mass is covered in columnar epithelial cells.{{citation needed|date=August 2020}}

==Sessile serrated adenoma== {{Main|Sessile serrated adenoma}} [[File:Sessile serrated adenoma 3 very high mag.jpg|thumb|Micrograph of a sessile serrated adenoma. H&E stain]] Sessile serrated adenomas are characterized by (1) basal dilation of the crypts, (2) basal crypt serration, (3) crypts that run horizontal to the basement membrane (horizontal crypts), and (4) crypt branching. The most common of these features is basal dilation of the crypts.

==See also== *Colorectal cancer *Colorectal polyp

==References== {{reflist}}

{{Digestive system neoplasia}}

Category:Digestive system neoplasia Category:Gross pathology Category:Large intestine Category:Rectal diseases