S4061 Endometriosis of the Small Bowel Can Mimic Crohn’s Disease in the Biopsy

Introduction: Endometriosis is a condition characterized by the presence of endometrial tissue outside the uterus, affecting approximately 10% of women in their childbearing age. In rare cases, endometriosis can involve the large or small bowel, potentially leading to bowel obstruction. Crohn's disease is a chronic inflammatory condition primarily affecting the terminal ileum. Clinical features can frequently overlap. Case Description/Methods: We present a consultation case of a 27-year-old woman who underwent an ileocaecal resection due to severe inflammatory processes. A histopathological assessment of a formalin-fixed paraffin-embedded block revealed foci of endometriosis in the subserosal space, muscularis propria, and submucosa of the small bowel wall. Adjacent mucosa displayed ulceration, chronic inflammation, and pyloric metaplasia (Figure 1). Discussion: Crohn's disease typically presents with chronic inflammation and ulceration in the terminal ileum. Pyloric metaplasia, a characteristic feature of Crohn's disease, has become less specific in recent years and can also be observed in conditions such as endometriosis. This similarity in histopathological features can lead to misdiagnosis in biopsy samples. Histopathological features of endometriosis involving the small intestine can closely mimic changes seen in Crohn's disease, potentially resulting in misdiagnosis. Pathologists must be aware of alternative possibilities that can cause cycles of damage and repair, which may deviate from a correct diagnosis.Figure 1.: Small bowel wall with foci of endometriosis and ulceration on scanning magnification.