Background: Insulinoma is the commonest functioning pancreatic neuroendocrine tumor causing hyperinsulinemic hypoglycemia.
Aim: This study is aimed to evaluate the clinical features, preoperative laboratory and imaging diagnosis and pathologic findings of insulinoma.
Methods: Data of the patients from 2001 to 2016 diagnosed as insulinoma in Tongji Hospital, China were retrospectively extracted and analyzed.
Results: A total of 40 patients were diagnosed as insulinoma with a male/female ratio of 0.68:1. The median onset age was 46.5 years. Nearly all the included patients presented neurological symptoms and 60% presented autonomic symptoms. More than 95% of the patients met the functional European Neuroendocrine Tumor Society criteria including glucose, insulin and C-peptide levels. The preoperative detection rates of ultrasonography, enhanced computed tomography, magnetic resonance imaging, and endoscopic ultrasonography were 60.50%, 84.95%, 80% and 83.3% respectively. The joint imaging examinations can markedly increase the detection rate. The mean tumor size was 1.89 ± 0.72 cm. Ki-67 index by histopathological diagnosis were all less than 20%. The positive rates of insulin, synaptophysin and chromogranin A were close to 100%.
Conclusion: Laboratory tests of glucose, insulin and C-peptide are reliable for preoperative diagnosis. Combination of the imaging examinations can improve the diagnosis.