RESUMO
CONTEXT: Endogenous hyperinsulinaemic hypoglycaemia in adults is most commonly caused by an insulinoma. Adult nesidioblastosis is rarely reported. To the best of our knowledge the presence of both insulinoma and nesidioblastosis has not been reported before. CASE REPORT: We report a case of a 35-year-old female presenting with neuroglycaemic symptoms. A supervised 72-hour fast confirmed hypoglycaemia in the presence of hyperinsulinaemia. Thorough pre-operative biochemical and radiological investigations, including selective splenic, superior mesenteric and portal venous sampling inferred a tentative diagnosis of adult nesidioblastosis. However, a grossly elevated insulin level within the splenic vein on a second set of venous sampling produced a high index of suspicion for the presence of an insulinoma. At surgical exploration both an insulinoma and nesidioblastosis were identified and confirmed by histological examination. CONCLUSION: We report an even rarer entity of concurrent insulinoma and nesidioblastosis.