Insulinoma presenting with post-prandial hypoglycaemia following fundoplication

Abstract

SummaryInsulinomas are rare neuroendocrine tumours that classically present with fasting hypoglycaemia. This case report discusses an uncommon and challenging case of insulinoma soon after upper gastrointestinal surgery. A 63-year-old man presented with 6 months of post-prandial hypoglycaemia beginning after a laparoscopic revision of Toupet fundoplication. Hyperinsulinaemic hypoglycaemia was confirmed during a spontaneous episode and in a mixed-meal test. Localisation studies including magnetic resonance imaging (MRI), endoscopic ultrasound (EUS) and gallium dotatate positron emission tomography (68Ga Dotatate PET) were consistent with a small insulinoma in the mid-body of the pancreas. The lesion was excised and histopathology was confirmed a localised well-differentiated neuroendocrine pancreatic neoplasm. There have been no significant episodes of hypoglycaemia since. This case highlights several key points. Insulinoma should be sought in proven post-prandial hyperinsulinaemic hypoglycaemia – even in the absence of fasting hypoglycaemia. The use of nuclear imaging targeting somatostatin and GLP1 receptors has improved accuracy of localisation. Despite these advances, accurate surgical resection can remain challenging.Learning points:Hypoglycaemia is defined by Whipple’s triad and can be provoked by fasting or mixed-meal tests.Although uncommon, insulinomas can present with post-prandial hypoglycaemia.In hypoglycaemia following gastrointestinal surgery (i.e. bariatric surgery or less commonly Nissen fundoplication) dumping syndrome or non-insulinoma pancreatogenous hypoglycaemia syndrome (NIPHS) should be considered.Improved imaging techniques including MRI, endoscopic ultrasound and functional nuclear medicine scans aid localisation of insulinomas.Despite advances in imaging and surgical techniques, accurate resection of insulinomas remains challenging.

Metastatic Insulinoma Presenting With Postprandial Hypoglycemia

“… 1 Several case reports discuss exclusive postprandial hypoglycemia as a presentation for a pancreatic NET. 7 , 8 , 9 Shreenivas et al 7 reported the case of a 47-year-old woman with postprandial hypoglycemia with isolated insulinoma diagnosed by a mixed-meal test, with insulin being the predominant hormone during hypoglycemia. Madathil et al 8 reported the case of a 60-year-old man with type 2 diabetes mellitus with elevated insulin levels at the time of postprandial hypoglycemia.…”

“…Madathil et al 8 reported the case of a 60-year-old man with type 2 diabetes mellitus with elevated insulin levels at the time of postprandial hypoglycemia. Qian et al 9 discussed postprandial hyperinsulinemic hypoglycemia in a 63-year-old man who underwent fundoplication; he was diagnosed with a mixed-meal test. To our knowledge, ours is the only case that describes exclusive postprandial hypoglycemia with a tumor that predominantly secretes proinsulin.…”

“…Patients with an insulinoma, a type of pancreatic neuroendocrine tumor (NET), typically present with fasting hypoglycemia. 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 Hypoglycemia is caused by inappropriate secretion of insulin and/or its precursors such as proinsulin. We present the case of a patient with metastatic proinsulin-secreting tumor presenting with exclusive postprandial hypoglycemia.…”

Occult insulinoma after oesophagectomy for oesophageal cancer-diagnostic challenges

“…2 In the context of previous gastrointestinal surgery, a form of dumping syndrome can mask hypoglycaemia from an underlying cause, such as an insulinoma. 3 affinity for type 2, 3 and 5 somatostatin receptors which are present in pancreatic neuroendocrine tumours; however, 68 Ga-DOTA-exendin-4 PET-CT-targeting glucagon-like peptide 1 receptor (GLP-1R) is considered the most sensitive diagnostic tool but it's not available in all centers. 6,7 The authors present a clinical case of a male patient who underwent oesophageal surgery for an oesophago-gastric junction adenocarcinoma and developed hypoglycaemic symptoms only in the post-operative period, caused by an undiagnosed insulinoma.…”

“…Indeed, insulinoma remains an important diagnosis to exclude in both post-prandial or fasting hyperinsulinaemic hypoglycaemia. 3…”