US QUIZ APRIL 2022

Case Report A 40-year-old woman with rectal bleeding underwent a colonoscopy. Her past medical history included dysmenorrhea controlled with a hormonal intrauterine device. Colonoscopy revealed a 15 mm polypoid lesion covered by eroded mucosa and luminal narrowing at 20 cm from the anal verge (Fig. 1A and 1B).  Histopathologic assessment of standard biopsy specimens was inconclusive. A pelvic magnetic resonance imaging demonstrated a 20 mm neoplastic lesion at sigmoid colon with endophytic growth. An endoscopic ultrasound (EUS) showed a 19×8 mm hypoechoic, round, well-demarcated lesion arising from the muscularis propria and involving superficial layers (Fig. 2). A EUS-guided fine-needle biopsy (EUS-FNB) was performed (Acquire 22 G needle, Boston ScientificTM, 2 passes) (Fig. 3).  Quiz Discussion Histopathological and cytological examination showed endometrial glands and stroma (Fig. 4), a pattern compatible with endometriosis. The patient is receiving treatment with monthly subcutaneous injection of gonadotropin-releasing hormone agonists. The most common location of extragenital endometriosis is the bowel. Rectosigmoid colon is involved in up to 93% of these cases. Patients may be asymptomatic or may present with dysmenorrhea, hematochezia, lower abdominal pain, constipation, diarrhea, tenesmus, and even bowel obstruction. An association of symptoms with the menstrual cycle is an important diagnostic clue (1). Endoscopically, bowel endometriosis may mimic subepithelial and neoplastic lesions as well as inflammatory, infectious or ischemic disease (2). Standard biopsies obtained during endoscopy are rarely sufficient for the diagnosis and imaging tests are not sensitive for the diagnosis. EUS features of rectosigmoid endometriosis have been reported as including a hypoechoic deep pelvic mass with an irregular or unclear margin infiltrating the anterior wall of the rectosigmoid colon (3). However, to confirm a diagnosis of rectosigmoid endometriosis, histologic identification of […]