A rare pancreatic neuroendocrine tumor with proinsulin-secreting activity

This paper presents a clinical case describing hypoglycemic condition with atypical symptoms in a young patient in the early postpartum period. Abdominal ultrasound revealed a large formation in the hook region of the pancreas, which was subsequently confirmed according to endoscopic ultrasound, CT and MRI. The idea of insulinoma was formed according to the presence of pancreatic formation, documented Whipple’s triad, and data on hyperinsulinism at the outpatient stage. However, the 72-hour fasting test showed no significant increase in insulin and C-peptide levels. After excluding other causes of hypoglycemia, the patient was suspected of having proinsulinoma, which was confirmed by increased blood proinsulin level. Gastropancreatoduodenal resection was performed. We detected a highly differentiated neuroendocrine pancreatic tumor with the expression of CD56, NSE, synaptophysin and chromogranin A, with a Ki-67 index of about 1%. After surgical treatment, hypoglycemic conditions were not observed.