Benign tumors
Adenoma (noncystic)

Author: Jaleh Mansouri, M.D. (see Authors page)

Revised: 1 October 2018, last major update August 2012

Copyright: (c) 2003-2018,, Inc.

PubMed Search: Adenoma appendix
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Cite this page: Mansouri, J. Adenoma (noncystic). website. Accessed January 22nd, 2019.
Definition / general
  • Very rare; by definition, no features of true invasion
  • Villous adenomas are also called low grade appendiceal mucinous neoplasms
  • Cystic adenomas are called cystadenomas (see below)
  • Sporadic, may be associated with colonic adenomas or familial adenomatous polyposis
Microscopic (histologic) description
  • Resemble colonic tubular, villous or tubulovillous adenomas
  • Cellular crowding, usually low grade dysplastic changes of nuclear elongation and stratification, pleomorphism and increased mitotic figures
  • Also mucin depletion
  • No invasion into appendiceal wall or high grade nuclear atypia