Signet Ring Cell Carcinoma of the Ampulla of Vater With Focal Neuroendocrine Differentiation of the Amphicrine Type: Report of a Case With Long

Carcinoma of the ampulla of Vater is an uncommon neoplasm and represents 0.5% of all gastrointestinal malignancies, being less common than carcinoma of the pancreas and bile ducts. The most common ampullary tumor is the adenocarcinoma with tubular growth pattern. Signet ring cell carcinoma is extremely rare. In this article, we report a case of signet ring cell carcinoma of the ampulla of Vater showing focal neuroendocrine amphicrine differentiation and intestinal phenotype, which occurred in a 49-year-old male who is still alive 7 years after surgery, without evidence of recurrence. This long-term survival might be attributed not only to the early stage of the disease but also to the neuroendocrine differentiation and the absence of genetic alterations