S6164 Look in the Ileum! Ileal Neuroendocrine Tumor: A Case Report and Review of the Literature

Introduction: Neuroendocrine tumors (NETs) of the small intestine, particularly in the ileum, are the most common small bowel neoplasms. Often clinically silent, these tumors may be metastatic at diagnosis, even when small. Terminal ileum intubation (TII) during screening colonoscopy is not routinely recommended but may uncover clinically significant pathology. Case Description/Methods: A 52-year-old man with chronic obstructive pulmonary disease, hypothyroidism, posttraumatic stress disease, and substance use disorder underwent screening colonoscopy without gastrointestinal symptoms. Findings included 2 small sessile adenomas in the ascending colon and a 9–10 mm submucosal nodule in the terminal ileum. Biopsy confirmed a well-differentiated grade 1 ileal NET. Computed tomography enterography revealed a localized 9 mm enhancing ileal lesion without lymphadenopathy or distant metastases. The patient underwent exploratory laparotomy with right hemicolectomy and terminal ileum resection. Final pathology confirmed a 0.7 cm grade 1 NET invading the muscularis propria with lymphovascular invasion; 6 of 16 lymph nodes were positive. Final stage: T2N1M0, Stage III. Postoperative surveillance was initiated. Three-month follow-up computed tomography revealed no disease recurrence. Discussion: This case illustrates the utility of TII in detecting asymptomatic yet biologically aggressive lesions. While TII is not part of routine colorectal cancer screening guidelines, it may yield important incidental findings. Small bowel NETs often present late due to their indolent nature and non-specific symptoms. In this case, despite its small size, the tumor demonstrated significant metastatic potential. Although advanced imaging (e.g., capsule endoscopy) exists, it is not routinely used in asymptomatic individuals, emphasizing the value of opportunistic detection via ileoscopy. Conclusion: Routine terminal ileoscopy during screening colonoscopy could improve detection of silent but clinically significant pathology such as ileal NETs. Larger studies are needed to determine whether TII should be integrated into standard colonoscopy protocols for average-risk individuals.