Ectopic Insulinomas in the Pelvis Secondary to Rectum Neuroendocrine Tumour

We describe a middle-aged woman with recurrent hypoglycaemia, who confirmed with rectum G1 neuroendocrine tumour (NET) 6 years ago. Biochemical assay showed high concentration of serum insulin and C-peptide associated with hypoglycaemia. Because of recurrent hypoglycaemia in June 2015, she underwent a resection of the tail of the pancreas. However, hypoglycaemia attack happened more frequently and severely. Ga-DOTA-NOC positron emission tomography/CT revealed five foci in the pelvis with intense uptake. Immediately after excision of the pelvic lesions, insulin and C-peptide decreased to normal levels promptly, and therefore, serum glucose increased significantly. Hypoglycaemia was disappeared, and insulin and C-peptide were normal at 2 years follow-up after surgery. Immunohistochemistry validated the primary rectum NET and pelvic tumours expressed with higher insulin, somatostatin receptor and glucagon-like peptide-1. This is the first reported ectopic pelvic insulinomas secondary to rectum NET, which may originate both from neuroendocrine cells in the rectum and pelvic tissues.