Anus & perianal
Other malignancies

Topic Completed: 1 April 2005

Revised: 19 August 2019

Copyright: (c) 2002-2019,, Inc.

PubMed Search: Leiomyosarcoma anal

Nat Pernick, M.D.
Page views in 2018: 51
Page views in 2019 to date: 82
Cite this page: Pernick N. Leiomyosarcoma. website. Accessed December 8th, 2019.
Definition / general
  • Most common stromal tumor of anus
  • Usually forms polypoid intraluminal mass; may be confused with a hemorrhoid
  • Often women, median age 58 years (range 24 - 79 years)
  • Presents with rectal obstruction or bleeding
  • Most do not die of disease (Am J Surg Pathol 2001;25:1121)
Gross description
  • Median 3 cm (range 2 - 5.5 cm)
  • Usually polypoid, ulcerated, intraluminal masses
Microscopic (histologic) description
  • Spindle cell tumors, usually resembling well differentiated smooth muscle cells
  • Oval to moderated elongated, often blunt ended, with distinctly eosinophilic cytoplasm, atypical nuclei, focal nuclear pleomorphism
  • Usually mucosal ulceration
  • High mitotic activity in all cases (26+ mitotic figures/10 HPF)
Positive stains
Negative stains
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