Endometriosis with colonic mucosal colonisation: a diagnostic confounder
Aims Secondary mucosal colonisation by a carcinoma originating from a distant site is a pattern of metastasis to the intestines and hepatobiliary tract and a mimic of primary neoplasia. Although endometriosis is considered benign, its ability to spread widely underscores its quasi-neoplastic nature. After noting that endometriotic glands can colonise the colonic mucosa along the basement membrane, mimicking metastatic disease, we conducted an intradepartmental review of intestinal specimens showing endometriosis obtained from 2016 to 2023 to characterise and quantify the incidence of this phenomenon. Methods Material from 38 lower gastrointestinal specimens with a primary or ancillary diagnosis of endometriosis was identified from our surgical pathology database. Slides were reviewed, documenting the extent and micro-anatomic location affected by endometriosis, with a focus on identifying examples showing mucosal colonisation. Results The most common site of involvement was the distal
