A case of rectal bleeding caused by digestive endometriosis resembling colon cancer.

A 42-year-old unmarried, nulliparous woman presented at our hospital with rectal bleeding. The patient had had iron deficiency anemia in the past. She had normal, regular menses with mild dysmenorrhea and had not taken hormonal drugs. Her physical examination was unremarkable. Colonoscopy revealed widespread polypoid mucosal thickening and luminal narrowing, along with erythema and edema, in the sigmoid colon. It was not possible to pass the endoscope beyond the lesion (●" Fig.1). Multiple endoscopic biopsies were taken, but histopathologic examination was nondiagnostic. An abdominal computed tomography (CT) scan revealed eccentric thickening of the wall of the sigmoid colon (●" Fig.2). The patient proceeded to laparotomy, which revealed that the lesion had penetrated the sigmoid colon to the posterior uterine wall. Segmental resection of the sigmoid colon with side-to-side anastomosis was performed. On pathological examination, beneath a 4-cm fleshy-grey polypoid mass, the colonic wall was thickened over a 5-cm length (●" Fig.3). Microscopy revealed polypoid endometriosis of the bowel. Native colonic mucosa was also observed around the areas of endometriosis (●" Fig.4). Intestinal endometriosis penetrating the bowel wall may lead to localized narrowing and obstruction [1]. Polypoid endometriosis is a rare variant of endometriosis that is characterized by multiple large polypoid masses that may resemble malignancies. Endoscopic ultrasound (EUS) can be used to determine the size, margins, and layer of origin, as well as additional morphologic features that can suggest the endometriosis. A hypoechoic lesion infiltrating the muscularis propria and the serosa of the rectal wall and extending outside the rectal wall may be seen during EUS [2]. The endoscopic appearance of the mucosa is not diagnostic, and endoscopic biopsies commonly yield specimens that are insufficient for pathologic diagnosis [3]. EUSguided fine needle aspiration (FNA) can be useful in the evaluation of rectosigmoid endometriosis [4]. Surgery is the gold-standard diagnostic method for endometriosis [5].