Appendix

Benign tumors

Tubular adenoma



Last author update: 10 May 2023
Last staff update: 10 May 2023

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PubMed Search: Tubular adenoma

Subramanya Sakaleshpura Mallikarjunappa, M.B.B.S., M.D.
Raul S. Gonzalez, M.D.
Page views in 2023: 2,381
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Cite this page: Mallikarjunappa SS, Gonzalez RS. Tubular adenoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/appendixtubularadenoma.html. Accessed February 26th, 2024.
Definition / general
  • Polypoid dysplastic lesion in the appendix, analogous to conventional adenomas in the colorectum
Essential features
  • Uncommon (not included in WHO classification of tumors of the appendix)
  • Tubulovillous adenomas are often resected as mass lesions, while small tubular adenomas may be encountered incidentally in colectomy specimens from patients with polyposis syndromes
  • Many adenocarcinomas of the appendix arise from adenomas
ICD coding
  • ICD-10: D12.1 - benign neoplasm of appendix
Epidemiology
Sites
  • Appendix
Pathophysiology
Clinical features
Diagnosis
Radiology description
Radiology images

Images hosted on other servers:

Double contrast barium enema

Abdominal CT scan

Prognostic factors
  • Appendiceal adenocarcinoma can arise from adenomas
  • Risk of progression likely increases with size and high grade dysplasia (as in the colon) but data are limited
Case reports
Treatment
Gross description
  • Similar to colorectal tubular adenomas, which can appear pedunculated, sessile, flat or depressed
  • May be seen arising from the appendix
  • Features of acute appendicitis and perforation can be seen if the adenoma presents accordingly (BMC Gastroenterol 2011;11:35)
Gross images

Images hosted on other servers:

Grossly visible appendiceal adenoma

Microscopic (histologic) description
  • Largely similar to colorectal tubular adenomas
  • Architecture is most often villous but may also be tubular
  • Predominantly composed of low grade dysplasia, with elongated, hyperchromatic nuclei and crowded glands
  • Foci of high grade dysplasia may show rounded cells with nucleoli, low polarity and cribriform architecture
  • Epithelial lining may have a somewhat hypermucinous appearance
  • Reference: Scand J Gastroenterol 1985;20:512
Microscopic (histologic) images

Contributed by Raul S. Gonzalez, M.D.
Tubular glands with elongated, hyperchromatic nuclei and crowded glands Tubular glands with elongated, hyperchromatic nuclei and crowded glands

Tubular glands with elongated, hyperchromatic nuclei and crowded glands

Crowded tubular and villous glands with elongated hyperchromatic nuclei Crowded tubular and villous glands with elongated hyperchromatic nuclei

Crowded tubular and villous glands with elongated hyperchromatic nuclei

Mucinous appearance

Mucinous appearance

Adenocarcinoma arising in adenoma

Adenocarcinoma arising in adenoma

Sample pathology report
  • Appendix, appendectomy:
    • Tubulovillous adenoma (2.1 cm)
    • Negative for high grade dysplasia or malignancy
    • Margin of resection negative
Differential diagnosis
  • Serrated polyp:
    • Can show areas of nuclear dysplasia but should also show additional areas of serrated glands with booting architecture and lacking conventional dysplasia
  • Appendiceal mucinous neoplasm:
    • May have villous areas and cytologic atypia but causes appendiceal dilation without polyp formation grossly
Board review style question #1

Which of the following is true about intestinal type adenomas of the appendix?

  1. They arise from low grade appendiceal mucinous neoplasms
  2. They can cause intussusception
  3. They have no risk of malignant progression
  4. They only occur in patients with familial adenomatous polyposis
Board review style answer #1
B. They can cause intussusception. Intestinal type adenomas of the appendix can cause appendicitis, bowel obstruction or perforation. They have no precursor lesion and may themselves progress to adenocarcinoma. They can occur sporadically or in patients with polyposis syndromes.

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Reference: Tubular adenoma
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