P2009 - Unmasking the Mimic: Rectal Endometriosis Deceptive Presentation as Rectal Cancer

Faisal Mehmood, MD¹, Hajra Jamil, MD², Hussein Al-Hamid, MD³, Joseph Fares, MD³, Hema Khurana, MBBS⁴, Gavin Levinthal, MD^3
1HonorHealth, Phoenix, AZ; ²Services Institute of Medical Sciences, Lahore, Punjab, Pakistan; ³HonorHealth, Scottsdale, AZ; ⁴GI Pathology Consultants of Arizona, Glendale, AZ

Introduction: Rectovaginal endometriosis is an endometriotic lesion more than 5 mm below the peritoneum. Symptoms include localized symptoms (deep dyspareunia, dyschezia). It is commonly associated with infertility. We present a case of a young woman who was diagnosed with rectal endometriosis after a complaint of rectal bleeding.

Case Description/Methods: A 34-year-old female with no pertinent medical history presented to clinic for evaluation of diarrhea with urgency and rectal bleeding for one year. She denied having abdominal pain, nausea, vomiting, or weight loss. She denied any family history of colon cancer.



Labs showed mild normocytic anemia with hemoglobin of 11.9 g/dL and otherwise normal serum chemistries, thyroid profile, and liver tests. Stool studies including clostridium difficile, cryptosporidium, giardia, ova and parasites were unremarkable. She underwent a colonoscopy and found to have a polypoid non-bleeding mass in the rectum 8cm proximal to the anus measuring 4cm (Figure A). Biopsies were taken, and pathology showed endometrial glands, stroma, and hemosiderin with no evidence of malignancy (Figure B). Those endometrial glands were positive for PAX-8 and ER, and stroma was positive for CD10. The histologic and immunophenotypic findings were consistent with rectal endometriosis. She was seen by gynecologic oncologist and underwent robotic assisted biopsy and fulguration of endometriosis. Intraoperatively, she was found to have extensive retroperitoneal endometriosis with normal adnexa (Figure C). It was decided not to do any resection or cautery to preserve fertility and prevent development of rectovaginal fistula.

Discussion: Among women with endometriosis, the reported prevalence of rectovaginal or bowel involvement ranges widely from 5 to 25 percent. There are no specific laboratory tests for diagnosis. Rectovaginal ultrasound is the preferred imaging modality. Colonoscopy is rarely useful to diagnose bowel endometriosis as lesions that penetrate the mucosa are unusual. However, patients with symptoms of rectal bleed, changes in bowel habits, or obstruction should undergo colonoscopy as a part of their evaluation. However, definitive diagnosis is made by histological evaluation of biopsied lesion. The main therapeutic options are medications for symptom control, systemic hormone-based medical therapy, or surgery. A multi-disciplinary surgical approach is typically required for surgical treatment.



Disclosures:


Faisal Mehmood, MD¹, Hajra Jamil, MD², Hussein Al-Hamid, MD³, Joseph Fares, MD³, Hema Khurana, MBBS⁴, Gavin Levinthal, MD³. P2009 - Unmasking the Mimic: Rectal Endometriosis Deceptive Presentation as Rectal Cancer, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.