Colon tumor
Mesenchymal tumors

Author: Raul S. Gonzalez, M.D. (see Authors page)

Revised: 28 February 2017, last major update February 2017

Copyright: (c) 2003-2017,, Inc.

PubMed Search: Leiomyoma [title] colon

Cite this page: Leiomyoma. website. Accessed July 23rd, 2018.
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

Images hosted on PathOut server

Contributed by Dr. Raul Gonzalez, University of Rochester Medical Center (USA):


Symplastic leiomyoma

Images hosted on other servers:

Leiomyoma of muscularis mucosa

Symplastic leiomyoma

Positive stains
Negative stains
Differential diagnosis