Colon
Carcinoma
Adenoma-like adenocarcinoma


Topic Completed: 14 April 2021

Minor changes: 14 April 2021

Copyright: 2002-2021, PathologyOutlines.com, Inc.

PubMed Search: Villous adenocarcinoma [title] colon

Raul S. Gonzalez, M.D.
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Cite this page: Gonzalez R. Adenoma-like adenocarcinoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/colontumorvillousadenocarcinoma.html. Accessed April 19th, 2021.
Definition / general
  • Well differentiated subtype of colorectal carcinoma with good prognosis that resembles villous adenoma on the surface (Anticancer Res 1998;18:2649)
  • Formally recognized by the WHO
Essential features
  • Very well differentiated subtype of colorectal carcinoma
  • Can mimic tubulovillous adenoma on biopsy, making diagnosis challenging
  • Very good prognosis, with metastasis uncommon
Terminology
Epidemiology
  • Approximately 3% - 5% of colorectal carcinomas have villous / adenoma-like features
Clinical features
  • Low rate of metastasis to lymph nodes and other organs
Diagnosis
  • Biopsy may resemble villous adenoma, so clinical / endoscopic correlation is essential
Gross images

Images hosted on other servers:

Villous tumor with central ulceration

Microscopic (histologic) description
  • Invasive carcinoma with architectural and cytologic features resembling villous adenoma
  • May have traditional invasive component or invade by pushing
  • Mucinous features often present
  • Epithelial islands in desmoplastic stroma is a helpful finding (Am J Surg Pathol 2004;28:1460)
  • May also have a component of conventional adenocarcinoma (Hum Pathol 2021;107:9)
Microscopic (histologic) images

Contributed by Raul S. Gonzalez, M.D.

Villous adenocarcinoma of colon



Contributed by Semir Vranic, M.D., Ph.D.

10×


CK7

20×

CDX2

CK20



Images hosted on other servers:

Abrupt transition from benign to malignant mucosa

Molecular / cytogenetics description
  • 24% of cases have microsatellite instability
Sample pathology report
  • Transverse colon, resection:
    • Adenoma-like adenocarcinoma of the colon, well differentiated, see synoptic report
Differential diagnosis
  • Villous adenoma:
    • Can be hard to distinguish on biopsy (subtle clues include gland distortion and desmoplasia)
Board review style question #1

    A patient presents with a colon mass, which is biopsied and then excised. What is the best diagnosis?

  1. Adenoma-like adenocarcinoma
  2. Colorectal adenocarcinoma, NOS
  3. Pure mucinous adenocarcinoma
  4. Tubulovillous adenoma with pseudoinvasion
Board review style answer #1
A. Adenoma-like adenocarcinoma

Comment Here

Reference: Adenoma-like adenocarcinoma
Board review style question #2
    Which of the following is true about adenoma-like adenocarcinoma of the colon?

  1. Always demonstrates microsatellite instability
  2. Always pure, without any component of conventional adenocarcinoma
  3. Can be difficult to diagnose on biopsy
  4. Has a high rate of lymph node and liver metastasis
Board review style answer #2
C. Can be difficult to diagnose on biopsy

Comment Here

Reference: Adenoma-like adenocarcinoma
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