Endometriosis with colonic mucosal colonisation: a diagnostic confounder

Area of Science:

• Gastroenterology
• Pathology
• Gynecology

Background:

• Endometriosis is a benign condition characterized by endometrial tissue outside the uterus.
• Widespread spread of endometriosis can mimic neoplastic processes.
• Secondary mucosal colonization by distant carcinomas is a known pattern of metastasis.

Purpose of the Study:

• To characterize and quantify the incidence of colonic mucosal colonization by endometriosis.
• To evaluate the potential of endometriosis to mimic metastatic disease in the gastrointestinal tract.

Main Methods:

• Retrospective review of 38 lower gastrointestinal specimens with endometriosis (2016-2023).
• Detailed examination of slides to document extent and location of endometriosis.
• Focus on identifying and characterizing mucosal colonization by endometriotic glands.

Main Results:

• Endometriosis involved the distal colon most frequently (23 cases).
• Mucosal involvement occurred in 8 cases (21%), with 4 cases showing seamless epithelial colonization.
• In 2 cases with mucosal involvement, symptoms suggested malignancy (mass or stricture).

Conclusions:

• Endometriosis occasionally colonizes colonic epithelium (10.5% of cases).
• This phenomenon can mimic metastatic disease or intraepithelial neoplasia.
• It can present as a misleading pattern, particularly when a mass or stricture is present.