Abstract In adults, nesidioblastosis is a very infrequent condition and a rare cause of symptomatic presentations. The diagnosis of nesidioblastosis may be difficult with functional and anatomical imaging modalities. “Slight focal” pancreatic abnormalities using 111In-pentetreotide imaging has been reported in patients with hyperinsulinaemic hypoglycaemia, confirmed histologically as nesidioblastosis. We describe a 60-year-old man who presented with a 1-year history of intermittent faecal urgency and refractory diarrhoea, non-specific laboratory results, negative imaging results (CT, MRI and EUS), a FNA biopsy that was inconclusive, but suggested an endocrine cell neoplasm, and a 111In-pentetreotide scan that showed a moderately intense focal uptake clearly localised to the pancreatic head on a low-dose fusion CT. The histopathology of the specimen confirmed the diagnosis of nesidioblastosis.