Tubular and ⁄or villous adenoma

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Author: Mikael Häggström [note 1]

Gross evaluation

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

Template:Colorectal adenoma criteria

Tubular or villous

Colorectal adenoma
Type Risk of containing malignant cells Histopathology Image
Tubular adenoma 2% at 1.5cm[2] Over 75% of volume has tubular appearance.[3] Tubular adenoma of the colon.jpg
Tubulovillous adenoma 20% to 25%[4] 25%-75% villous[3] Micrograph of tubulovillous adenoma.jpg
Villous adenoma 15%[5] to 40%[4] Over 75% villous[3] Villous adenoma of the colorectum (high power view).jpg

Length of villi must be at least twice the depth of the normal mucosal thickness.[6]

Differential diagnoses

Hyperplastic polyp
Hyperplastic Polyp[7] Tubular Adenoma[7]
Nu dysplasia Dysplasia
Proliferative zone restricted to base Proliferative zone starting at the surface
Gland lining cells mature at the surface No surface maturation
Colorectal adenocarcinoma
Colorectal adenocarcinoma, not otherwise specified

edit
Colorectal carcinoma (mainly adenocarcinoma) is distinguished from an adenoma (mainly tubular and ⁄or villous adenomas) mainly by invasion through the muscularis mucosae.[8]

Also, adenocarcinoma also commonly displays:[9]

  • Varying degrees of gland formation with tall columnar cells
  • Frequenty desmoplasia
  • Dirty necrosis, consisting of extensive central necrosis with granular eosinophilic karyorrhectic debris. Garland of cribriform glands are frequently found in their vicinity.

Further workup

Dissecting pools of mucin at the base of any adenoma should be evaluated for the possibility of mucinous carcinoma.[6]

Notes

  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

References

  1. Monica Dahlgren, Janne Malina, Anna Måsbäck, Otto Ljungberg (1997-02-13). Lilla utskärningen.
  2. Minhhuyen Nguyen. Polyps of the Colon and Rectum. MSD Manual. Last full review/revision June 2019
  3. 3.0 3.1 3.2 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. 
  4. 4.0 4.1 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. 
  5. Alnoor Ramji. Villous Adenoma Follow-up. Medscape. Updated: Oct 24, 2016
  6. 6.0 6.1 Cite error: Invalid <ref> tag; no text was provided for refs named stanford-criteria
  7. 7.0 7.1 . Hyperplastic Polyp of the Colon and Rectum - Differential diagnoses. Stanford University School of Medicine. Retrieved on 2019-09-30.
  8. Robert V Rouse. Colorectal Adenoma Containing Invasive Adenocarcinoma. Stanford University School of Medicine.
  9. Robert V Rouse. Adenocarcinoma of the Colon and Rectum. Stanford University School of Medicine. Original posting/updates: 1/31/10, 7/15/11, 11/12/11

Image sources