Editing Colorectal polyps


Abnormal protrusion of mucosa into bowel lumen, resulting from overgrowth of epithelial lining

== '''Classification by endoscopic appearance''' ==

* Pedunculated
* Sessile


== '''Classification by histological appearance''' ==

=== Non-neoplastic polyps ===

** '''Inflammatory      polyps''' (pseudopolyps)
*** Found in regions of healing       inflammation - contains inflammatory cells along with epithelial/stromal       components
*** Irregularly shaped islands       of intact mucosa neighbouring areas of mucosal ulceration/regeneration
*** Typically seen in       association with IBD
*** Can be associated with       surrounding dysplasia in patients with IBD
*** No intrinsic neoplastic       potential, but can be large, mimicking a neoplasm
***
** '''Hamartomatous      polyps'''
*** Tissue normally found at       that site, but growing in a disorganised mass
*** Juvenile polyps
**** Hamartomatous lesions that        consist of a lamina propria and dilated cystic glands, rather than        increased numbers of epithelial cells
**** Can be diagnosed at any        age, although more common in childhood
**** Not associated with        increased CRC risk unless in the setting of juvenile polyposis syndrome
*** Peutz-Jeghers polyps
**** Hamartomatous lesion of        glandular epithelium supported by smooth muscle cells that is        contiguous with the muscularis mucosa
**** Usually, but not always,        associated with PJS
*** Cronkhite-Canada syndrome
*** Can cause obstruction or       bleeding, otherwise don't necessarily need to be removed
***
* '''Sessile     serrated lesions'''
** '''Hyperplastic      polyps'''
*** Most common benign polyps -       no malignant potential
*** Typically <5mm, in       rectosigmoid
*** Typically sessile, smooth       surface, slight pink discolouration
*** Consist of elongated       colonic crypts with a papillary configuration of epithelial cells       without atypia
*** Lots of hyperplastic polyps       in the rectum is not associated with cancer elsewhere, and does not       shorten the recommended screening interval
***
** '''Sessile      serrated adenomas'''
*** Previously classified as       hyperplastic
*** More prevalent in right       colon and more common in women
*** 'Traditional serrated       adenomas' are a separate subtype and are often found in rectosigmoid
*** Endoscopic: smooth,       'cloud-like' surface, often flat or sessile, and can have mucus       covering.
*** Histopathology:       combinations of adenomatous and hyperplastic polyps, sharing features of       both types including colonic crypts with a saw-toothed serrated       configuration and nuclear atypia.
**** 37% have 'significant'        dysplasia
**** 11% have CIS
**** Thought to be the        precursor lesion to sporadic MSI-H colon cancers (CpG island        hypermethylation phenotype)
**** Activation of BRAF        oncogene is a features of many SSAs
*** Disproportionately high       risk for progression to cancer - possibly faster progression, easier to       miss, incomplete removal
***

=== '''Neoplastic     polyps (adenoma)''' ===

** As opposed to benign - these      polyps have cellular atypia and all have malignant potential
** Most common neoplastic type      (two thirds of all polyps)
** 30-50% have multiple - if      you find one, keep looking
** Overall prevalence 25% at 50      years old, 50% by 70 years
** Grow at 0.5mm/year
** 5% progress to cancer over      10 years
*** High-risk if >1cm,       sessile, high-grade dysplasia, or villous component
** Tubular adenomas - 70-80% of      polyps removed - branched tubular glands
***
** Villous adenomas - long      finger-like projections of surface epithelium (serpentine appearance)
***
** Tubulovillous - elements of      both types

=== '''Malignant     polyps''' ===

** Histologic examination      reveals a focus of carcinoma that has invaded through the muscularis      mucosa
** Depth of penetration is      crucial - Haggitt classification
*** Level 0: Carcinoma is       limited to the mucosa - carcinoma-in-situ
*** Level 1: Carcinoma invading       into the submucosa, limited to the head of the polyp
*** Level 2: Carcinoma invading       to the level of the neck (junction of the head and the stalk)
*** Level 3: Carcinoma invading       any part of the stalk
*** Level 4: Carcinoma invading       into the submucosa of the colon wall, below the level of the stalk, but       above the muscularis propria. 12-25% lymph node metastases - usually       suggest resection.
***
*** Sessile polyps with       invasion of the muscularis mucosa are by definition Haggitt level 4.
** Kikuchi classification:      depth of submucosal invasion correlates with increased risk of lymph node      metastasis
*** Sm1: invasion into the       upper third of the mucosa
*** Sm2: Invasion into the       middle third of the mucosa. 8-10% lymph node metastasis risk.
*** Sm3: Invasion into the       lower third of the mucosa 25% metastasis risk.
** Indications for completion      segmental colectomy for malignant polyps: (in these cases, the risk of      residual cancer and lymph node metastasis is >10%)
*** Pedunculated Haggitt level       4
*** Sessile Kikuchi level Sm2       or Sm3
*** Histological poor       differentiation
*** Lymphovascular invasion
*** Incomplete removal or close       resection margins
*** Other high-risk polyps       based on risk calculators

== '''Presentation''' ==

* Usually asymptomatic
* Complications:
** Bleeding
** Obstruction
** Malignant transformation

== '''Post-polypectomy surveillance''' ==

* See separate topic under     'Endoscopy'

== '''Malignancy risk''' ==

== '''Metastases risk''' ==

* Pedunculated
** Dutch T1 pedunculated polyp      calculator <nowiki>https://t1crc.com/calculator/pedunculated/</nowiki>
*** Differentiation
*** Haggitt level
*** Budding
*** Poorly-differentiated       clusters
*** LVI
*** Status of muscularis       mucosae
** Malignantpolyp.com

[[Category:Colorectal]]
[[Category:Intern education]]