Expect the unexpected: Endometriosis mimicking a rectal carcinoma in a post-menopausal lady

Altered bowels habits along with rectal mass in an elderly would point toward a rectal cancer. We report an unusual case of a post-menopausal lady who presented with these complaints. We had difficulties in establishing a pre-operative diagnosis. With a tentative diagnosis of a rectal cancer/gastrointestinal stromal tumor, she underwent a laparoscopic anterior resection. On histopathology, this turned out to be endometriosis. Bowel endometriosis is an uncommon occurrence. That it occurred in a post-menopausal lady was a very unusual finding. We discuss the case, its management, and the relevant literature.