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Anus and perianal area

Other malignancies


Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 16 April 2013, last major update April 2005
Copyright: (c) 2003-2013, PathologyOutlines.com, Inc.


● 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 to 5.5 cm)
● Usually polypoid, ulcerated, intraluminal masses

Micro 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

● Actin

Negative stains

● CD117

End of Anus and perianal area > Other malignancies > Leiomyosarcoma

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