Subcentimeter Ileal Neuroendocrine Tumor Resection for Obscure Gastrointestinal Bleeding Followed by Pacemaker-Treated Sick Sinus Syndrome: A Case Report.

BACKGROUND Obscure gastrointestinal bleeding (OGIB) denotes recurrent hemorrhage after nondiagnostic bidirectional endoscopy. In overt presentations with suspected small-bowel origin, capsule endoscopy, deep enteroscopy, and multiphase computed tomographic enterography (CTE) can improve lesion detection and operative planning. However, subcentimeter small-intestinal neuroendocrine tumors (siNETs) may remain undetected unless cross-sectional imaging enables targeted exploration. CASE REPORT A 72-year-old man presented with 2 days of melena and vague abdominal discomfort in the absence of hematemesis, hematochezia, weight loss, focal pain, or carcinoid features. Esophagogastroduodenoscopy and colonoscopy were nondiagnostic. Multiphase CTE localized an 11×8 mm enhancing mural nodule in the distal small bowel. Diagnostic laparoscopy with conversion to a limited laparotomy and intraoperative enteroscopy enabled precise localization, segmental ileal resection with mesentery, primary anastomosis, and appendectomy. Pathology findings comprised a grade 1 siNET measuring 0.8×0.6 cm with subserosal invasion, negative margins, and metastasis in 1 of 2 lymph nodes (pT3 pN1, Ki-67 index 2%). The postoperative surgical course was uncomplicated; however, profound bradycardia with syncope unmasked sinus node dysfunction, requiring dual-chamber pacemaker implantation, after which the patient remained clinically stable. CONCLUSIONS In older patients with overt OGIB and negative bidirectional endoscopy, early multiphase CTE can identify a small hypervascular ileal lesion, guiding targeted intraoperative enteroscopy and oncologic resection. Because nodal metastasis may occur despite a subcentimeter primary tumor, resection should include appropriate mesenteric lymphadenectomy. Vigilant perioperative cardiac rhythm monitoring is warranted because clinically significant bradyarrhythmias may require permanent pacemaker implantation.