Endoscopic localization and tattooing of a proinsulinoma for minimally invasive resection.

Hypoglycemia can be common in patients using insulin injections or certain antidiabetes medications. In rare cases, hypoglycemia can be caused by a pancreatic insulinoma. We report a case of a 33-year-old woman found to have severe recurrent hypoglycemia. Diagnostic studies such as continuous glucose monitoring and a hospitalized fast provided biochemical evidence for a proinsulinoma. After abdominal multidetector contrast-enhanced computerized tomography failed to detect pancreatic abnormalities, endoscopic ultrasonography identified and localized a 9-mm pancreatic tail lesion. At the time of endoscopy, the lesion was tattooed with ultrasonographic guidance for subsequent laparoscopic visualization and curative resection.