Colon

Polyps

Tubulovillous / villous adenoma


Editorial Board Members: Raul S. Gonzalez, M.D., Naziheh Assarzadegan, M.D.
Editor-in-Chief: Debra L. Zynger, M.D.
Carolina Martinez Ciarpaglini, M.D., Ph.D.

Last author update: 21 June 2022
Last staff update: 21 June 2022

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PubMed Search: Tubulovillous / villous adenoma

Carolina Martinez Ciarpaglini, M.D., Ph.D.
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Cite this page: Martinez Ciarpaglini C. Tubulovillous / villous adenoma . PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/colontumortvadenoma.html. Accessed December 3rd, 2022.
Definition / general
Essential features
  • Recognized as the precursor lesion of chromosomal unstable colorectal cancer (Pathologica 2021;113:218)
  • Low grade dysplasia is an intrinsic feature
  • Associated with oncogene KRAS mutation in 50% of cases
ICD coding
  • ICD-10: D12.6 - benign neoplasm of colon, unspecified
Sites
Pathophysiology
  • Conventional adenoma carcinoma sequence with oncogene (KRAS) activation and tumor suppressor (APC, SMAD4 and TP53) inactivation
  • Associated with chromosomal unstable colorectal cancer (Cancer Biol Med 2016;13:120)
Clinical features
Diagnosis
  • Screening or surveillance colonoscopy identifies and removes lesion, followed by tissue diagnosis
Prognostic factors
  • Villous or tubulovillous histology is associated with increased risk of colorectal neoplasia: 16.8% versus 9.7% compared with tubular adenomas
  • Increased risk of malignant transformation in cases with high grade dysplasia (↑ 1.77x) (Gastroenterology 2012;143:844)
  • Risk of recurrence with malignancy after excision is associated with piecemeal endoscopic resection (Surg Endosc 2021;35:2500)
Case reports
Treatment
  • Endoscopic resection
  • When possible, en bloc resection should be the goal for the management (Surg Endosc 2021;35:2500)
Gross description
  • Pedunculated or sessile polypoid lesions with macroscopic finger-like projections
Gross images

Contributed by Carolina Martinez Ciarpaglini, M.D., Ph.D.
Large villous polyp

Large villous polyp

Giant villous adenoma

Giant villous adenoma



Images hosted on other servers:
Sessile villous adenoma

Sessile villous adenoma

Pedunculated villous adenoma

Pedunculated villous adenoma

Villous surface

Villous surface

Detailed view of villous projections

Detailed view of villous projections

Adenocarcinoma arising in villous adenoma

Adenocarcinoma arising in villous adenoma

Microscopic (histologic) description
  • Low grade dysplasia is a constituent feature
  • Epithelial, finger-like projections, away from the muscularis mucosae, formed by fibrovascular cores lined by dysplastic epithelium (villous architecture)
    • Percentage of villosity defines diagnostic terminology
    • 20 - 80% = tubulovillous adenoma
    • > 80% = villous adenoma
  • Crowded pseudostratification of cells with elongated nuclei occupying the basal half of the cytoplasm
  • Pleomorphism and atypical mitoses should be absent or minimally present
  • Mitotic activity and minimal loss of cell polarity are allowed
  • Architecturally, the crypts should maintain a resemblance to normal colon, without significant crowding, cribriform or complex forms
  • Squamous metaplasia as solid nests of squamous cells in direct continuity with adenomatous glands may be seen in about 0.4% of colorectal adenomas (Histopathology 2021;78:348)
  • Paneth cell metaplasia is a frequent finding (17 - 23%), especially in proximal locations; osseous metaplasia has been reported (Histopathology 2021;78:348)
  • Neuroendocrine metaplasia refers to the presence of scattered foci of neuroendocrine cells that lack significant nuclear atypia, mitotic activity or necrosis; these cells comprise < 30% of the lesion (Ann Diagn Pathol 2019;42:69)
  • Clusters of neuroendocrine metaplasia are usually < 2 mm and limited to the lamina propria without disturbing the overall architecture (Histopathology 2021;78:348)
  • Ectopic crypt foci are a frequent finding (J Clin Pathol 2016;69:1063)
  • High grade dysplasia can be seen (carcinoma in situ or intraepithelial / intramucosal carcinoma are not recommended terms)
    • Increased nucleus to cytoplasm ratio
    • Significant loss of cell polarity: nuclear stratification through the entire thickness of the epithelium
    • Round nuclei with open appearing chromatin and increasingly prominent nucleoli
    • Significant pleomorphism and atypical mitoses
    • Abnormal architecture includes cribriform structures with back to back glands, prominent glandular budding and intraluminal papillary tufting (StatPearls: Villous Adenoma [Accessed 31 May 2022])
  • Poor interobserver agreement for assessment of the villous component and high grade dysplasia have been demonstrated (Am J Surg Pathol 2013;37:427)
Microscopic (histologic) images

Contributed by Carolina Martinez Ciarpaglini, M.D., Ph.D., Jijgee Munkhdelger, M.D., Ph.D. and Andrey Bychkov, M.D., Ph.D.
Neuroendocrine metaplasia Neuroendocrine metaplasia

Neuroendocrine metaplasia

Squamous metaplasia Squamous metaplasia Squamous metaplasia

Squamous metaplasia


High grade dysplasia High grade dysplasia High grade dysplasia

High grade dysplasia

Low grade dysplasia

Low grade dysplasia

Villous architecture

Villous architecture


Giant rectal villous adenoma

Giant rectal villous adenoma

Focal eosinophilic change

Focal eosinophilic change

Ectopic crypt foci

Ectopic crypt foci

Cut section

Cut section

Pedunculated polyp

Pedunculated polyp


Neuroendocrine metaplasia (marker expression)

Neuroendocrine metaplasia (marker expression)

Neuroendocrine metaplasia (marker expression)

Neuroendocrine metaplasia (Ki67)

Squamous metaplasia (CK5/6)

Squamous metaplasia (CK5/6)

Squamous metaplasia (beta catenin)

Squamous metaplasia (beta catenin)

Virtual slides

Images hosted on other servers:
Villous adenoma

Villous adenoma

Positive stains
Negative stains
Molecular / cytogenetics description
Sample pathology report
  • Colon, polyp at 12 cm, endoscopic polypectomy:
    • Tubulovillous adenoma with high grade dysplasia

  • Colon, polyp at 14 cm, endoscopic polypectomy:
    • Villous adenoma
Differential diagnosis
Board review style question #1

A colon polyp is resected. The image shown above is representative of the lesion. What is your diagnosis?

  1. Composite adenoma neuroendocrine carcinoma
  2. Composite adenoma neuroendocrine tumor
  3. Tubulovillous adenoma with high grade dysplasia
  4. Tubulovillous adenoma with squamous metaplasia
Board review style answer #1
D. Tubulovillous adenoma with squamous metaplasia

Comment here

Reference: Tubulovillous / villous adenoma
Board review style question #2
Which of the following is true about villous adenoma?

  1. Frequently associated with KRAS mutations
  2. Precursor lesion in the serrated pathway of colorectal development
  3. Presents the same risk of malignant transformation as tubular adenoma
  4. Routine screening of MMR proteins for Lynch syndrome in this lesion is useful
Board review style answer #2
A. Frequently associated with KRAS mutations

Comment here

Reference: Tubulovillous / villous adenoma
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