Subcentimeter Ileal Neuroendocrine Tumor Resection for Obscure Gastrointestinal Bleeding Followed by Pacemaker-Treated Sick Sinus Syndrome: A Case Report.
Llerena-Velastegui J, Bermeo-Sevilla G, et al. • The American journal of case reports • 2026
A subcentimeter ileal neuroendocrine tumor causing obscure gastrointestinal bleeding was identified by multiphase computed tomographic enterography after nondiagnostic bidirectional endoscopy, and despite the tumor measuring only 0.8×0.6 cm, nodal metastasis was present, underscoring the need for mesenteric lymphadenectomy; postoperative sick sinus syndrome required dual-chamber pacemaker implantation.
Key Findings
Background
Multiphase computed tomographic enterography (CTE) successfully localized a subcentimeter hypervascular ileal lesion after nondiagnostic bidirectional endoscopy in a patient with obscure gastrointestinal bleeding.
The patient was a 72-year-old man presenting with 2 days of melena and vague abdominal discomfort without hematemesis, hematochezia, weight loss, focal pain, or carcinoid features.
Esophagogastroduodenoscopy and colonoscopy were both nondiagnostic.
Multiphase CTE identified an 11×8 mm enhancing mural nodule in the distal small bowel.
Cross-sectional imaging enabled targeted operative planning when standard endoscopy failed.
Results
Diagnostic laparoscopy with conversion to limited laparotomy and intraoperative enteroscopy enabled precise localization and oncologic resection of the small ileal neuroendocrine tumor.
The surgical approach included diagnostic laparoscopy converted to a limited laparotomy.
Intraoperative enteroscopy was used for precise lesion localization.
The procedure included segmental ileal resection with mesentery, primary anastomosis, and appendectomy.
The postoperative surgical course was described as uncomplicated.
Results
Pathology confirmed a grade 1 small-intestinal neuroendocrine tumor (siNET) with nodal metastasis despite its subcentimeter size.
The tumor measured 0.8×0.6 cm with subserosal invasion and negative surgical margins.
Metastasis was found in 1 of 2 lymph nodes examined.
Pathologic staging was pT3 pN1.
Ki-67 index was 2%, consistent with grade 1 classification.
The presence of nodal metastasis in a subcentimeter primary tumor supports the need for mesenteric lymphadenectomy regardless of tumor size.
The bradyarrhythmia manifested in the postoperative period following ileal resection.
The condition presented as profound bradycardia with syncope.
Dual-chamber pacemaker implantation was required to treat the sinus node dysfunction.
After pacemaker implantation, the patient remained clinically stable.
The authors conclude that vigilant perioperative cardiac rhythm monitoring is warranted in this patient population.
Conclusions
The authors conclude that nodal metastasis may occur despite a subcentimeter primary siNET, supporting resection with appropriate mesenteric lymphadenectomy.
The primary tumor was 0.8×0.6 cm yet demonstrated metastasis in 1 of 2 regional lymph nodes.
Staging was pT3 pN1 despite the small tumor size.
The authors explicitly state: 'Because nodal metastasis may occur despite a subcentimeter primary tumor, resection should include appropriate mesenteric lymphadenectomy.'
Early multiphase CTE is recommended in older patients with overt OGIB and negative bidirectional endoscopy.
What This Means
This case report describes a 72-year-old man who came to medical attention with dark, tarry stools (melena) but had no clear source of bleeding found on standard upper and lower endoscopy. A specialized CT scan of the small intestine (called CT enterography) found a small tumor — less than a centimeter across — in the lower part of the small intestine (ileum). Surgery was performed using a combination of laparoscopy and a small open incision, along with a camera passed through the intestine during the operation to find the exact location of the tumor. The tumor was removed along with nearby lymph nodes. Lab analysis showed it was a slow-growing neuroendocrine tumor (a type of tumor that can arise from hormone-producing cells in the gut), and despite its tiny size, it had already spread to one nearby lymph node.
After surgery, the patient developed a dangerously slow heart rate and fainting episodes, which revealed an underlying problem with the heart's natural pacemaker (sick sinus syndrome). This required implantation of an artificial pacemaker, after which the patient recovered well. This research suggests that even very small intestinal neuroendocrine tumors can spread to lymph nodes, meaning that surgery should always include removal of the surrounding lymph node tissue, not just the tumor itself. It also suggests that advanced CT imaging of the small bowel should be considered early when standard endoscopy fails to find the source of gastrointestinal bleeding.
The case also highlights that older patients undergoing abdominal surgery for gastrointestinal bleeding may have undiagnosed heart rhythm problems that only become apparent during or after the procedure. This research suggests that careful heart rhythm monitoring throughout the surgical period is important, as some patients may need additional cardiac treatment such as pacemaker implantation to remain safe and stable.
Llerena-Velastegui J, Bermeo-Sevilla G, Nunez-Medina F, Zambrano-Herdoiza J, Jimbo-Sotomayor R, Sanchez X. (2026). Subcentimeter Ileal Neuroendocrine Tumor Resection for Obscure Gastrointestinal Bleeding Followed by Pacemaker-Treated Sick Sinus Syndrome: A Case Report.. The American journal of case reports. https://doi.org/10.12659/AJCR.953537