Calcitonin-secreting pancreatic neuroendocrine tumor: A case report and literature review

Calcitonin-secreting is rare in patients with pancreatic neuroendocrine carcinoma, which is prone to misdiagnosis and needs more attention from clinicians. Here, we present a case of pancreatic head mass with an unexpected high peripheral level of calcitonin and was first misdiagnosed as medullary thyroid carcinoma (MTC). The only significant findings were intermittent defecation, a mass filled with abundant blood supply in the pancreatic uncinate process on contrast-enhanced computerized tomography, and hypercalcitoninemia. Postsurgical pathology confirmed that the mass was a pancreatic neuroendocrine tumor (pNET G2), and preoperatively elevated calcitonin and procalcitonin levels have also decreased to normal. Elevated calcitonin levels are rarely observed in other pathological conditions, such as pancreatic neuroendocrine neoplasms (pNENs), rather than MTC. We report a rare case and review the literature, broadening the phenotypic spectrum of this disease with its unique endocrine manifestations.