Localization of islet-cell hyperplasia: value of pre- and intraoperative arterial stimulation and venous sampling

Arterial stimulation and venous sampling was effective in the localization of β‐cell hyperplasia of the pancreas in the islets of Langerhans in an 84‐year‐old woman. The patient presented with repeated episodes of unconsciousness and hypoglycemia. She was first suspected of having insulinoma, but diagnostic imaging failed to reveal any tumors. Arterial stimulation and venous sampling (ASVS) and percutaneous transhepatic portal venous sampling (PTPS) were performed to localize the tumor. By ASVS, increases in immuno reactive insulin (IRI) were noted in renal vein blood samples (because a splenorenal shunt was present) after splenic arterial stimulation and venous sampling, and PTPS revealed a stepup in IRI from splenic venous blood samples. Preoperative diagnosis suggested β‐cell hyperplasia in the pancreas tail. Intraoperative ultrasound failed to find a tumor. Intraoperative ASVS showed the site of increase IRI as the pancreas tail, so distal pancreatectomy and splenectomy were performed. However, hypoglycemia was observed constantly after this operation. Relaparotomy, causing additional resection, was conducted to confirm the precise location and to remove the residual β‐cell hyperplasia of the pancreas. At the second resection, the existing part of β‐cell hyperplasia was confirmed through intraoperative ASVS, and additional resection of the pancreas body and neck was performed. At this time, complete removal of the residual β‐cell hyperplasia was confirmed through ASVS. The hypoglycemia and impaired consciousness disappeared after the operation, and the patient's blood sugar level was maintained at a normal level. Pathological findings revealed islets of Langerhans hyperplasia extending to 1 cm in the pancreas tail region. We conclude that pre‐ and intraoperative ASVS is a useful test for β‐cell hyperplasia, which is difficult to diagnose through ordinary imaging techniques.