Neuroendocrine ampullary tumors: spectrum of disease including the first report of a neuroendocrine carcinoma of non-small cell type.

Primary neuroendocrine tumors of the ampulla of Vater are rare. These tumors, like those of the respiratory tract and remainder of the gastrointestinal tract, appear along a histologic spectrum of increasing malignancy from low-grade carcinoid tumors to high-grade small cell undifferentiated cancers. We herein describe the characteristics of these ampullary neoplasms and report the first case of a neuroendocrine carcinoma of non-small cell type, which represents the middle of this histologic continuum. This tumor seems to follow a more aggressive course than the carcinoid tumor but less aggressive than its small cell counterpart.