Abstract
Endometriosis is a benign, estrogen-dependent condition, usually occurring in menstruating and, rarely, in postmenopausal women, in which endometrial glands and stroma grow ectopically outside the uterus. Most often, ectopic endometrial tissue is found within the pelvis and nearby structures. However, endometrial tissue within the upper gastrointestinal tract is very rare and can be a source of bleeding and abdominal pain. Here, we report a case of a 71-year-old postmenopausal woman with hematochezia and diffuse abdominal pain, who was found to have pyloric endometriosis, the pathogenesis of which we will briefly explore.