Terminal Ileal Endometriosis Masquerading as Crohn's Disease: A Rare Cause of Small Bowel Obstruction and Perforation in a Middle-Aged Woman.

Endometriosis is a chronic inflammatory condition affecting 5-10% of women of reproductive age, most commonly involving pelvic organs. Gastrointestinal endometriosis, particularly at the terminal ileum, is rare and can clinically mimic other conditions such as Crohn's disease, posing significant diagnostic challenges. We report the case of a 45-year-old woman with no prior medical or gynecologic history who presented with a 1-week history of nausea, vomiting, abdominal pain, and obstipation. Imaging studies revealed terminal ileal lesions, and colonoscopy identified a large obstructive polypoid lesion 4 cm proximal to the ileocecal valve. She underwent laparoscopic ileocolic resection, which revealed an obstructed and perforated terminal ileum. Histopathological analysis demonstrated florid granulation tissue, subserosal fibrosis, and a purulent exudate, with endometriotic inclusions comprising endometrial glands and stroma in the terminal ileum and appendix. The ileal and colonic mucosa were unremarkable, and no reactive lymphadenopathy was found. A final diagnosis of ileal endometriosis was made. Postoperatively, the patient recovered well, required no additional medical therapy, and experienced a significant improvement in symptoms without recurrence. This case highlights an unusual presentation of terminal ileal endometriosis causing small bowel obstruction and perforation, masquerading as Crohn's disease. The absence of typical gynecologic symptoms or mucosal abnormalities underscores the diagnostic complexity. Recognition of this rare entity is crucial, as timely surgical intervention can be curative and significantly enhance patient outcomes. This case reinforces the importance of maintaining a broad differential diagnosis in women presenting with unexplained gastrointestinal symptoms and ileal lesions. LEARNING POINTS: This case underscores the rare and deceptive presentation of ileal endometriosis mimicking Crohn's disease, culminating in small bowel obstruction and perforation in a patient without any prior history or gynecologic symptoms.What sets this case apart is the presence of both ileal and appendiceal endometriotic inclusions, in the absence of typical mucosal involvement or prior diagnosis of endometriosis.The diagnosis was only confirmed postoperatively through histopathology, reinforcing the importance of considering endometriosis in the differential diagnosis of terminal ileal lesions-even in patients beyond peak reproductive years and with no classic symptoms.