Introduction: Iron deficiency anemia is a common gastroenterological presentation. Endoscopic investigation is standard practice. We describe a case of iron deficiency anemia in a patient who was lost to follow‐up, before re‐presenting with clinically significant overt gastrointestinal bleeding, leading to a diagnosis of metastatic small bowel neuroendocrine tumor.

Case report: A 50‐year‐old Maori man was referred to the gastroenterology outpatient department for investigation of iron deficiency anemia. He had an episode of rectal bleeding 1 month earlier, when he had been investigated with upper gastrointestinal endoscopy and colonoscopy, both of which were unremarkable. He had subsequently been booked in for a capsule endoscopy but failed to attend the procedure and his clinic appointment and was lost to follow‐up. One year later, he presented to the emergency department with maroon‐colored feces, pre‐syncope, and an acute drop in hemoglobin level from 112 to 68 g/L. An urgent upper gastrointestinal endoscopy was normal, and a computed tomography angiogram was unremarkable except for minor fat stranding in the greater omentum. Subsequent colonoscopy with deep ileal intubation to 30 cm showed ileal blood and a non‐ulcerated 10 mm submucosal lesion. A retrograde double balloon enteroscopy was therefore performed, finding an ulcerated submucosal lesion at 150 cm from the ileocecal valve (Fig. 1). Of note, four other submucosal lesions with intact overlying mucosa were seen throughout the jejunum and ileum. A laparoscopy was performed, with the intent of small bowel resection; however, the procedure was aborted due to extensive peritoneal carcinomatosis. Histology from an intraoperative biopsy confirmed metastatic low‐grade neuroendocrine tumor. He was referred to oncology for ongoing management.

Conclusion: This case demonstrates the indolent nature of small bowel neuroendocrine tumors, where iron deficiency may be the only manifestation. Early diagnosis can lead to curative surgical management. Iron deficiency anemia in a young man is a red flag and warrants thorough investigation.