Type III gastric neuroendocrine tumor associated with a hyperplastic polyp presenting with severe iron deficiency anemia: a case report

Type III gastric neuroendocrine tumors (G-NETs) are rare, sporadic, and aggressive gastric neuroendocrine neoplasms that are typically diagnosed after the onset of gastrointestinal symptoms or metastatic disease. Presentation with isolated severe iron deficiency anemia (IDA) is uncommon. We report a case most consistent with a locally advanced type III G-NET associated with a hyperplastic polyp, diagnosed during evaluation of severe iron deficiency anemia in a young woman without gastrointestinal symptoms. A 39-year-old woman with hypertension and type 2 diabetes mellitus presented with progressive fatigue and dyspnea on exertion. Laboratory evaluation revealed severe microcytic IDA with a hemoglobin level of 4 g/dL. Esophagogastroduodenoscopy demonstrated a large ulcerated gastric body mass with submucosal tumor-like morphology. Colonoscopy was unremarkable. Histopathological examination revealed a WHO grade 2 NET arising within a hyperplastic polyp, with no evidence of atrophic gastritis on background gastric biopsies. Staging with 68Ga-DOTATOC PET/CT demonstrated regional lymphadenopathy without distant metastases. The patient underwent subtotal gastrectomy with regional lymphadenectomy. Surgical pathology was consistent with a well-differentiated WHO grade 2 gastric NET, with the bulk of the tumor in the submucosa abutting the muscularis propria without infiltrating it, and metastatic involvement of two perigastric lymph nodes. Surgical margins were negative. Surveillance CT imaging at 3 and 12 months, EGD at 12 months, and 68Ga-DOTATOC PET/CT at 24 months showed no evidence of recurrence or metastatic disease. Her IDA resolved completely following supportive hematologic therapy (blood transfusion and intravenous iron supplementation) and surgical resection. Type III gastric NET may rarely present solely with severe IDA in the absence of gastrointestinal symptoms. To our knowledge, only a limited number of similar cases have been reported. This case highlights the importance of considering upper endoscopic evaluation in patients with severe or unexplained IDA, even in premenopausal women. Early recognition of type III G-NET is important because of their aggressive behavior and metastatic potential, and timely surgical management can result in favorable oncologic outcomes with resolution of anemia when combined with supportive hematologic therapy.