Endometriosis, an unusual case of rectal mass with bloody stool and bowel habit changes

Dear Editor,

Endometriosis related dysmenorrhea, deep dyspareunia, dyschezia and dysuria are not uncommon among fertile women. Frequently noted anatomic distribution of endometriosis includes ovary, cul‐de‐sac, and uterus [1]. However, gastrointestinal (GI) tract endometriosis is rarely found. Here we report a case of recto‐sigmoid mass relate to endometriosis.

This 43‐year‐old woman with past history of chocolate cyst post excision presented with intermittent bloody stool passage for 2 months. She also had the symptoms of left lower abdominal pain and decreased frequency of stool passage. Her abdominal pain was not related to food intake and stool passage. Bloody stool episode occurred especially during her menstrual cycle. Except for tenderness over left lower abdomen, physical examination including rectal digital examination was unremarkable.

Colonoscopy examination revealed a sessile mass occupied about 1/3 circumferential lumen. The mucosa was eroded and with subtle color changes, from 8 cm to 15 cm above the anal verge (Fig. 1A). Endoscopic biopsy showed benign rectal mucosa with chronic inflammatory infiltration in the edematous lamina propria. Contrast computed tomography of the abdomen showed thickening colonic wall along the recto‐sigmoid area extending about 7.0 cm in length (Fig. 1B). Blood examinations including CEA level were within normal range.

Figure 1.

(A) Colonoscopy revealed a sessile mass occupied about 1/3 circumferential lumen with subtle color changes and mucosa erosion (white arrows). (B) Computed tomography of the abdomen survey disclosed wall thickening at the recto‐sigmoid colon (white arrows). (C) Operation picture showed total obliteration of Cou‐de‐sac, the deep infiltrating endometriosis (asterisk) was extended over bilateral uterosacral ligaments and rectum. (D) Endometrial tissue is noted at submucosa (yellow arrow) near the colon mucosal base (100×).

Laparoscopic intervention showed a long segment of submucosal lesion along rectum with lumen stricture and bloody ascites (Fig. 1C). Low anterior resection and end‐to‐side colo‐colostomy were performed subsequently. Microscopically, the colon tissue showed multiple embedded foci of endometrial tissue including both glandular and stromal parts in submucosa, muscular wall and subserosal fibroadipose tissue (Fig. 1D).

Endometriosis implants to GI tract consist about 5.4% of all endometriosis. The most involving area is rectum (about 70–80%), and followed by sigmoid, appendix, and terminal ileum [2]. The most common symptoms of recto‐sigmoid endometriosis are bowel habit change, abdominal pain, and hematochezia. These symptoms may mimic malignancy, inflammatory bowel disease, or ischemic colitis, which pose the difficulties to accurate diagnosis.

There is no gold standard for the non‐invasive diagnosis of GI involvement of endometriosis. Computed tomography with distention of the colon by rectal enterolysis (MSCTe) may present enhanced solid nodules, contiguous or penetrating the colonic wall, but the depth infiltrated by nodules may be underestimated [3]. Colonfiberscopic examination may appear polyps or masses, thickened wall, mucosa change with erythema or granularity, and even narrowing of the bowel lumen. However, it is difficult to distinguish from malignancy if endometriosis only invades submucosa layer. Kim et al. reported five cases of endometriosis present with fungating ulcerative colonic mass with non‐specific biopsy findings [4]. Milone et al. have shown low diagnosis rate of bowel endometriosis by colonoscopy [5]. However, close infiltration of the endometrial tissue to the mucosa layer, as shown in this patient, implicates the potential diagnostic yield of full thickness biopsy by large biopsy forceps before invasive intervention.

Laparoscopy or laparotomy is usually the definite diagnostic procedure and treatment of endometriosis. During the operation, surgeons can make complete evaluation of genital and intestinal endometriosis and get tissue proof for accurate diagnosis. Major complications included rectovaginal fistula, rectosigmoid anastomosis dehiscence and bowel occlusion.

Endometriosis presented with recto‐sigmoid mass was an uncommon finding. It is important to consider this association in a fertile female patient with recurrent abdominal pain, defecation abnormality and bloody stool.