Intestinal endometriosis diagnosed by mucosal cutting biopsy: a case report

A 46-year-old, female patient was admitted to our hospital after testing positive on a fecal occult blood test. Colonoscopy revealed a submucosal tumor in the lower rectum with poor extension. Computed tomography and magnetic resonance imaging revealed a 23-mm, extramural mass with homogeneous enhancement. Endoscopic ultrasound showed an heterogeneous, hypo-echoic, extramural growth, mainly in the fourth layer of the intestinal mucosa. For definitive diagnosis, a mucosal cutting biopsy was performed using a disposable endo-knife. Pathological analysis of the biopsy specimen revealed endometrial cells that were positive for estrogen receptors. Based on this finding, intestinal endometriosis was diagnosed.