Other nonneoplastic


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PubMed search: Colon endometriosis

Raul S. Gonzalez, M.D.
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Cite this page: Gonzalez RS. Endometriosis. website. Accessed July 13th, 2024.
Definition / general
  • Endometriosis arising within colon
Essential features
  • Similar to endometriosis elsewhere: can cause clinical symptoms; histology shows endometrial glands, endometrial stroma and hemosiderin
  • Malignant transformation is rare
  • Up to 33% with endometriosis have involvement of large or small intestine
  • Usually rectosigmoid or rectovaginal septum (Med Sci Monit 2000;6:787)
  • Can involve any portion of colonic wall, from mucosa to serosa
Clinical features
  • Typically incidental but can cause pain, obstruction or diarrhea
  • Rarely associated with neoplasms or precancerous changes (Am J Surg Pathol 2000;24:513)
Case reports
Gross description
  • Serosal and subserosal nodules < 5 cm; smooth muscle hypertrophy may cause obstruction
  • Gray cut surface with minute areas of hemorrhage; can cause adhesions if subserosal
Gross images

Contributed by @Andrew_Fltv on Twitter
Endometriosis Endometriosis


Microscopic (histologic) description
  • Endometrial glands and stroma plus hemosiderin in deeper layers of colon; usually surrounded by smooth muscle
  • Epithelium may have inflammation and ulcers, simulating inflammatory bowel disease or solitary rectal ulcer syndrome
  • Often infiltrates along nerves of bowel wall (Hum Reprod 2004;19:996)
  • Mucosa usually normal; bowel wall may be fibrotic; cilia help distinguish endometrial glands from colonic glands
Microscopic (histologic) images

Contributed by Raul S. Gonzalez, M.D. and @Andrew_Fltv on Twitter
Colonic endometriosis Colonic endometriosis Colonic endometriosis

Colonic endometriosis



Images hosted on other servers:

Within colonic mucosa

Present in wall of colon

Infiltration along nerves

Positive stains
Negative stains
Differential diagnosis
Sample pathology report
  • Ascending colon, resection:
    • Colon with multiple mural and serosal foci of endometriosis
    • Negative for malignancy.
    • Margins of resection unremarkable.
    • Two benign lymph nodes.
Board review style question #1

Which of the following is true about colonic endometriosis?

  1. It is most common in the ascending colon
  2. It is typically incidental
  3. It never contains hemosiderin histologically
  4. It often contains endometrioid adenocarcinoma
Board review style answer #1
B. It is typically incidental

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Reference: Endometriosis
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