Colon
Mesenchymal tumors
Leiomyoma


Topic Completed: 29 January 2021

Minor changes: 29 January 2021

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PubMed Search: Leiomyoma [title] colon


Raul S. Gonzalez, M.D.
Page views in 2020: 4,210
Page views in 2021 to date: 1,899
Cite this page: Gonzalez RS. Leiomyoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/colontumorleiomyoma.html. Accessed May 12th, 2021.
Definition / general
  • Benign smooth muscle proliferation of colon
Essential features
  • Benign incidental tumor usually arising in muscularis mucosae
Terminology
  • Symplastic leiomyoma refers to benign tumor with bizarre nuclear atypia and possibly increased mitotic activity
Sites
  • 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
Diagnosis
  • Generally discovered incidentally during colonoscopy
Case reports
Treatment
  • 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 S. Gonzalez, M.D.

Leiomyoma

Symplastic leiomyoma

Positive stains
Negative stains
Sample pathology report
  • Sigmoid colon, polypectomy:
    • Leiomyoma
Differential diagnosis
Board review style question #1
What is the most common location of origin for leiomyomas of the colon?

  1. Muscularis mucosae
  2. Muscularis propria
  3. Submucosal blood vessels
  4. Subserosal blood vessels
Board review style answer #1
A. Muscularis mucosae

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