Pitfalls in diagnosing a pancreatic neuroendocrine tumor: a case report

Pancreatic neuroendocrine tumors are a rare subset of pancreatic neoplasms. We report the case of a 33-year-old female patient who was admitted to the Diabetes Clinic of Craiova, Romania, due to a two-year history of episodic neuroglycopenic hyperinsulinemic hypoglycemic symptoms, suggestive for insulinoma associated with facial and upper trunk flushing characteristic to carcinoid syndrome. During these episodes, the laboratory investigations showed hypoglycemia (38 mg/dL), hyperinsulinemia (54.72 mu U/mL) and normal values of beta-hydroxybutyrate, chromogranin A, serotonin, anti-insulin antibodies and urinary levels of 5-hydroxyindoleacetic acid. Endoscopic ultrasound with SonoVue and 3T MRI revealed an 18.3/16.3 mm hypervascular tissular mass situated in the uncinate process of the pancreatic head in close contact with the superior mesenteric vein without invasion and no other detectable secondary lesions in the pancreas or any other abdominal viscera. Patient underwent enucleation of pancreatic tumor. The histological and immunohistochemical findings indicated a functional well-differentiated pancreatic neuroendocrine tumor, G1 category according to the World Health Organization (WHO) criteria, with uncertain behavior (Ki67 index was 3%), confined to the pancreas, but with tumoral invasion of the delimiting conjunctive capsule. No evidence of tumoral CK19 staining, mitoses and necrosis, angioinvasion or extra-pancreatic invasion was observed. A post-operative nine-month follow-up showed resolution of hypoglycemic symptoms, normalized blood glucose and insulin levels and no evidence of recurrence. Our case report highlights the pitfalls in diagnosing a functional pancreatic neuroendocrine tumor due to atypical symptoms, the difficulty of identification and precise location of the small-size tumor and uncertain histopathological and immunohistochemical behavior.