Pancreatic Neuroendocrine Tumors Presenting with Hypercalcitonemia

ABSTRACT Objective: Pancreatic neuroendocrine tumors (pNETs) can be associated with discrete clinical syndromes due to the secretion of a variety of bioactive substances that are used to confirm the diagnosis and as potential tumor markers. Calcitonin (Ct) is mainly secreted by medullary thyroid carcinoma (MTC) but is also rarely secreted by pNETs, occasionally leading to diagnostic confusion. We report the diagnosis of 4 patients with metastatic pNETs and associated Ct secretion who were initially evaluated for thyroid pathology. Methods: We describe the histories of 4 patients who were referred for evaluation of thyroid diseases and proved to have metastatic pNETs and associated Ct secretion. One of the patients had erroneously undergone thyroidectomy as hypercalcitonemia was attributed to MTC. Results: Patients presented with variable Ct levels (4-fold up to 35-fold elevations), and all had thyroid nodules that were considered the cause of hypercalcitonemia. Ultrasonography and fine-needle aspiration c...