Neuroendocrine tumor with diarrhea: not always the usual suspects - a case report of metastatic calcitoninoma with literature review.

We describe a case of a 59-year-old man without relevant past medical history, presenting with chronic diarrhea and weight loss. Extensive laboratory analysis, stool cultures and gastro- and ileocolonoscopy could not identify a diagnosis. Abdominal imaging revealed a mass in the uncinate process of the pancreas with mesenteric adenopathies and liver metastases. Fine needle aspiration was compatible with a pancreatic neuroendocrine tumor with low proliferative capacity (Ki-67 <1%). Immunohistochemical staining was positive for calcitonin and serum calcitonin levels were clearly elevated. Surprisingly,