Colon (tumor & nontumor)
Mesenchymal tumors

Topic Completed: 1 February 2017

Minor changes: 31 July 2020

Copyright::2003-2019,, Inc.

PubMed Search: Leiomyoma [title] colon

Raul S. Gonzalez, M.D.
Page views in 2019: 4,730
Page views in 2020 to date: 2,461
Cite this page: Gonzalez R. Leiomyoma. website. Accessed August 14th, 2020.
Definition / general
  • Benign smooth muscle proliferation of colon
Essential features
  • Benign incidental tumor arising in muscularis mucosae
  • "Symplastic leiomyoma" refers to benign tumor with bizarre nuclear atypia and possibly increased mitotic activity
  • Most gastrointestinal tract leiomyomas arise in colon
  • Majority arise in rectosigmoid (Mod Pathol 2001;14:950)
Clinical features
  • Benign
  • More common in men
  • Median age is 62 years
  • Generally discovered incidentally during colonoscopy
Case reports
  • Total excision is adequate treatment
Clinical images
Images hosted on other servers:

Leiomyoma on colonoscopy

Endoscopic removal of a leiomyoma

Gross description
  • Firm, white, well delineated nodule or polyp, generally < 1 cm
Microscopic (histologic) description
  • Well differentiated smooth muscle cells with red fibrillar cytoplasm, arranged in fascicles and arising from muscularis mucosae (Arch Pathol Lab Med 2011;135:1311)
  • Usually no mitotic activity or necrosis
  • Symplastic leiomyomas demonstrate significant atypia and possibly increased mitotic activity
Microscopic (histologic) images
Contributed by Raul Gonzalez, M.D.


Symplastic leiomyoma

Positive stains
Negative stains
Differential diagnosis
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