Sigmoid Endometriosis Diagnosed by Endoscopic Ultrasound Fine Needle Aspirate

Purpose: Diagnostic evaluation of submucosal lesions in the sigmoid colon often requires surgical intervention. The use of endoscopic ultrasound fine needle aspiration (EUS-FNA) is an accepted method for investigation of submucosal lesions in the lumen of the GI tract. This case illustrates the value of EUS-FNA in a submucosal sigmoid colon lesion. A 36-year-old female presented with one month of left lower quadrant abdominal pain. Her past medical history was only significant for depression. There was no fever, constipation, diarrhea, or rectal bleeding associated with the pain. Abdominal exam revealed tenderness in the left lower quadrant without mass. A contrasted CT scan showed fatty mesenteric stranding around the left ovary and sigmoid colon. Pelvic exam and pelvic ultrasound were unremarkable. She was treated with antibiotics for presumed diverticulitis. Colonoscopy performed six weeks later showed submucosal nodules in the sigmoid colon, 20 cm from the anal verge. The nodules were smooth and not mobile. Biopsies showed normal colonic mucosa. EUS revealed a 20×23 mm nodular hypoechoic mass that involved the muscularis propria of the sigmoid colon. There was a transmural irregular extension of this mass into the pericolonic tissue. EUS-FNA was performed with 3 passes into the mass for cytology. The cytological studies revealed reactive appearing glandular epithelial cells with no evidence of goblet cells. There were focal hemosiderin-laden macrophages present. Immunohistochemical studies were performed on the tissue and identified the epithelium to be cytokeratin 7 positive and cytokeratin 20 negative. Endometrial stromal cells present were CD 10 positive and scattered histiocytes were KP-1 positive. The cytomorphology of the specimen and immunohistochemical profile was diagnostic of endometriosis. Diagnosis of colonic mural endometriosis is challenging, and this case illustrates the clinical utility for EUS-FNA of submucosal lesions in the sigmoid colon.[figure1]Figure