Colorectal polyp

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Author: Mikael Häggström [note 1]

Endoscopic biopsies   edit

Gross examination

Further information: Colon

Tissue selection and trimming

There is a separate article for the Grossing of minimally invasive colorectal surgery.

Depending on sample format:[1]

  • Biopsies and polyps of <4 mm are embedded in their entirety. Samples less than 0.3 mm should be stained with eosin to avoid getting lost processing.
  • Polyps 4-8 mm with short stem or without stem: Identify the excision surface and divide the polyp longitudinally through the excision surface.
  • Polyps > 8 mm with a stem long enough to make it possible to take a transverse, whole slice from the stem closest to the excision surface: First, take a transverse slice through the peripheral portion of the stem, encompassing the entire circumference. Then take a 3-4 mm thick slice longitudinally through the polyp and the middle of the stem, after which the two remaining parts on either side are cut into equally thick slices, parallel to the previous slice.
  • Polyps >8 mm with short stem or without stem: Identify the excision surface and cut out a 3-4 mm thick disk that extends longitudinally through the center of the excision surface. Then divide the two remaining portions into equally thick slices, parallel to the previous slice.
  • Polyps that come in parts: Pick out the largest pieces, which are cut as similar as possible to above. Small fragments are sieved and embedded in a separate box.

Gross reporting

  • Polyp and/or fragment sizes
  • Presence or absence of stem of polyps

Example, for a gastrointestinal biopsy:

Labeled: "Sigmoid colon biopsy". The specimen is received in formalin and consists of 4 fragments of pink-tan tissue with a vaguely recognizable mucosal surface, mixed with food-like material. The fragments measure 0.2-0.3 cm in greatest dimension. The entire specimen is submitted for microscopic examination in one cassette.

Microscopic evaluation

Major signs

Look particularly for these, to help sorting into proper diagnosis in next section:

Main types

Consider at least the following conditions:

Incidences and malignancy risks of various types of colorectal polyps.[2]
Colorectal polyps
Type Risk of containing malignant cells Histopathology Image
Hyperplastic polyp 0% No dysplasia.[3]
  • Mucin-rich type: Serrated (“saw tooth”, pictured) appearance, containing glands with star-shaped lumina.[4] Crypts that are elongated but straight, narrow and hyperchromatic at the base. All crypts reach to the muscularis mucosae.[4]
  • Goblet cell-rich type: Elongated, fat crypts and little to no serration. Filled with goblet cells, extending to surface, which commonly has a tufted appearance.[4]
Hyperplastic Polyp of the Rectum (14060044206).jpg
Tubular adenoma 2% at 1.5cm[5] Low to high grade dysplasia[6] Over 75% of volume has tubular appearance.[7] Tubular adenoma of the colon.jpg
Tubulovillous adenoma 20% to 25%[8] 25%-75% villous[7] Histopathology of tubulovillous adenoma.jpg
Villous adenoma 15%[9] to 40%[8] Over 75% villous[7] Villous adenoma of the colorectum (high power view).jpg
Sessile serrated adenoma (SSA)[10]
  • Basal dilation of the crypts
  • Basal crypt serration
  • Crypts that run horizontal to the basement membrane (horizontal crypts)
  • Crypt branching.
Sessile Serrated Adenoma, Transverse Colon, 0.4 cm (3632298679).jpg
Traditional serrated adenoma
  • Protuberant villi with slit-like serrations.[11]
  • Pseudostratified epithelial columnar cells shapes.[11]
  • Eosinophilic cytoplasm and dark, pencil-like nuclei.[11]
  • Golblet cells are present.[11]
Traditional Serrated Adenoma of Colon (5203904731).jpg
Colorectal adenocarcinoma 100%
  • In carcinoma in situ (Tis): cancer cells invading into the lamina propria, and may involve but not penetrate the muscularis mucosae. Can be classified as "high-grade dysplasia", because prognosis and management are essentially the same.[3]
  • Invasive adenocarcinoma: Extending through the muscularis mucosae into the submucosa and beyond.[3]
Adenocarcinoma highly differentiated (rectum) H&E magn 400x.jpg

Other benign

Colonic lipoma, a benign polyp, here being submucosal and pedunculated.

If a more specific diagnosis cannot readily be made, clearly non-malignant colorectal polyps may simply be reported as such.

Further information: Evaluation of tumors

Microscopy report

It should include:[12]

  • Size of polyp (from gross examination)
  • Histopathologic type
  • Depth of growth and/or infiltration
  • Whether the resection is radical

Optionally, it can include degree of differentiation and/or dysplasia.


Micrograph of tubulovillous adenoma.jpg
50 mm large tubulovillous adenoma with up to high grade columnar epithelial dysplasia. No infiltration. Radical excision.

If multiple polyps are submitted in one container, you may count the amount of each polyp type if you can, but if the amount of fragments in microscopy exceeds the amount of fragments purportedly submitted, then you can simply write "fragments of", like the following example:

Fragments of tubular adenoma and hyperplastic polyp.

More details are given in main articles of histopathologic types.

  See also: General notes on reporting


  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Patholines:Authorship for details.

Main page


  1. Monica Dahlgren, Janne Malina, Anna Måsbäck, Otto Ljungberg (1997-02-13). Lilla utskärningen.
  2. References for pie chart are located at separate image description page.
  3. 3.0 3.1 3.2 Finlay A Macrae. Overview of colon polyps. UpToDate. This topic last updated: Dec 10, 2018.
  4. 4.0 4.1 4.2 Robert V Rouse (2010-01-31). Hyperplastic Polyp of the Colon and Rectum. Stanford University School of Medicine. Last updated 6/2/2015
  5. Minhhuyen Nguyen. Polyps of the Colon and Rectum. MSD Manual. Last full review/revision June 2019
  6. Robert V Rouse. Adenoma of the Colon and Rectum. Original posting/last update : 1/31/10, 1/19/14
  7. 7.0 7.1 7.2 Bosman, F. T. (2010). WHO classification of tumours of the digestive system . Lyon: International Agency for Research on Cancer. ISBN 92-832-2432-9. OCLC 688585784. 
  8. 8.0 8.1 Amersi, Farin; Agustin, Michelle; Ko, Clifford Y (2005). "Colorectal Cancer: Epidemiology, Risk Factors, and Health Services ". Clinics in Colon and Rectal Surgery 18 (03): 133–140. doi:10.1055/s-2005-916274. ISSN 1531-0043. 
  9. Alnoor Ramji. Villous Adenoma Follow-up. Medscape. Updated: Oct 24, 2016
  10. Rosty, C; Hewett, D. G.; Brown, I. S.; Leggett, B. A.; Whitehall, V. L. (2013). "Serrated polyps of the large intestine: Current understanding of diagnosis, pathogenesis, and clinical management ". Journal of Gastroenterology 48 (3): 287–302. doi:10.1007/s00535-012-0720-y. PMID 23208018. 
  11. 11.0 11.1 11.2 11.3 Enoch Kuo, M.D., Raul S. Gonzalez, M.D.. Colon - Polyps - Traditional serrated adenoma. Topic Completed: 1 February 2018. Minor changes: 1 October 2020
  12. Monica Dahlgren, Janne Malina, Anna Måsbäck, Otto Ljungberg. Stora utskärningen. KVAST (Swedish Society of Pathology). Retrieved on 2019-09-26.

Image sources