Tubular and ⁄or villous adenoma

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Author: Mikael Häggström [notes 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

Criteria

Tubular adenoma with low-grade dysplasia.

Dysplastic changes should involve at least the upper half of the crypts and the luminal surface.[2]

  • Nuclear dysplasia is mandatory to diagnose adenoma. It involves:
  • Nuclear atypia: Enlarged hyperchromatic nuclei (that is, dark purple) that are oval or frequently elongated, and with high nucleus to cytoplasm ratio.[2][3]
  • Other cellular atypia: Often nuclear stratification, nuclear crowding (that is, nuclei are bunched-up) and loss of polarity[2]
  • Always changes in gland architecture, such as:[2]
  • Enlarged crypts
  • Gland budding, or otherwise irregular glands[2]
  • Mucin depletion is often seen, but is not required[2]
  • Goblet cell reduction.

Differential diagnoses

Hyperplastic polyp
Hyperplastic polyp[4] Tubular adenoma[4]
Nu dysplasia Dysplasia
Proliferative epithelium restricted to base Proliferative epithelium present at the surface
Gland lining cells mature at the surface No surface maturation
Colorectal carcinoma
Colorectal adenocarcinoma (in this case, not otherwise specified).

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Colorectal carcinoma (mainly adenocarcinoma) is distinguished from an adenoma (mainly tubular and ⁄or villous adenomas) mainly by invasion through the muscularis mucosae.[5]

In carcinoma in situ (Tis), cancer cells invade into the lamina propria, and may involve but not penetrating the muscularis mucosae. This can be classified as an adenoma with "high-grade dysplasia", because prognosis and management are essentially the same.[6]

Also, carcinoma also commonly displays:[7]

  • 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.

Low or high grade

In low-grade lesions, the crypts should maintain a resemblance to normal colon.[8]

High-grade dysplasia:
-Substantial stratification
-Nuclear pleomorphism
-Atypical mitoses
-Increased nucleus to cytoplasm ratio
-Prominent nucleoli
Typical findings in low-grade versus high-grade tubular and ⁄or villous adenoma
Low-grade[8] High grade[8]
Crowding Pseudo-stratification to early stratification More substantial stratification
Nuclear pleomorphism and atypical mitoses Absent or minimally present Present
Loss of cell polarity Minimal More significant
Crowding, cribriform, or complex architecture No significant Present

High grade lesions also typically have:

  • Cribriform architecture, consisting of juxtaposed gland lumens without stroma in between, with loss of cell polarity. Rarely, they have foci of squamous differentiation (morules). This should be distinguished from cases where piles of well-differentiated mucin-producing cells appear cribriform. In such piles, nuclei show regular polarity with apical mucin, and their nuclei are not markedly enlarged.
  • Increased nucleus to cytoplasm ratio.[8]
  • More "open" appearing nuclei with increasingly prominent nucleoli[8]
  • Back-to-back glands[8]

Tubular or villous

Colorectal adenoma
Type Risk of containing malignant cells Histopathology Image
Tubular adenoma 2% at 1.5cm[9] Over 75% of volume has tubular appearance.[10] Tubular adenoma of the colon.jpg
Tubulovillous adenoma 20% to 25%[11] 25%-75% villous[10] Histopathology of tubulovillous adenoma.jpg
Villous adenoma 15%[12] to 40%[11] Over 75% villous[10] Villous adenoma of the colorectum (high power view).jpg

Length of villi must be at least twice the depth of the normal mucosal thickness.[2]

Further information: Evaluation of tumors

Further workup

Look for and evaluate any lymph nodes in the tissue specimen, for possible malignancy.

Dissecting pools of mucin at the base of any adenoma should be evaluated for the possibility of mucinous carcinoma.[2]

Report

  • Adenoma size
  • Tubular, tubulovillous or villous adenoma.
  • Whether it is radically resected.

If any lymph nodes are found in tissue sample, report the presence or absence of malignancy in any of them.

See also: General notes on reporting

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. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Robert V Rouse. Adenoma of the Colon and Rectum. Stanford University School of Medicine. Original posting/last update : 1/31/10, 1/19/14
  3. Mehran Taherian; Saran Lotfollahzadeh; Parnaz Daneshpajouhnejad; Komal Arora. Tubular Adenoma. National Center for Biotechnology Information. Last Update: May 30, 2020.
  4. 4.0 4.1 . Hyperplastic Polyp of the Colon and Rectum - Differential diagnoses. Stanford University School of Medicine. Retrieved on 2019-09-30.
  5. Robert V Rouse. Colorectal Adenoma Containing Invasive Adenocarcinoma. Stanford University School of Medicine.
  6. Finlay A Macrae. Overview of colon polyps. UpToDate. This topic last updated: Dec 10, 2018.
  7. 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
  8. 8.0 8.1 8.2 8.3 8.4 8.5 David J. Myers; Komal Arora. Villous Adenoma. StatPearls, National Center for Biotechnology Information. Last Update: June 18, 2019.
    -"This book is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/)"
  9. Minhhuyen Nguyen. Polyps of the Colon and Rectum. MSD Manual. Last full review/revision June 2019
  10. 10.0 10.1 10.2 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. 
  11. 11.0 11.1 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. 
  12. Alnoor Ramji. Villous Adenoma Follow-up. Medscape. Updated: Oct 24, 2016