Colon

Carcinoma

Adenoma-like adenocarcinoma



Topic Completed: 14 April 2021

Minor changes: 21 April 2021

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PubMed Search: Villous adenocarcinoma[TI] OR adenoma-like adenocarcinoma[TI]

Raul S. Gonzalez, M.D.
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Cite this page: Gonzalez RS. Adenoma-like adenocarcinoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/colontumorvillousadenocarcinoma.html. Accessed October 28th, 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.

5x

10x

10x

10x


CK7

20x

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

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

  1. It always demonstrates microsatellite instability
  2. It can be difficult to diagnose on biopsy
  3. It has a high rate of lymph node and liver metastasis
  4. It is always pure, without any component of conventional adenocarcinoma
Board review style answer #2
B. It can be difficult to diagnose on biopsy

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Reference: Adenoma-like adenocarcinoma
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