Large cell neuroendocrine carcinoma of the ampulla of vater.

We report a large cell neuroendocrine carcinoma arising in the ampulla of Vater. The patient, a 74-year-old woman, presented with a 3-cm ulcerated mass located in the ampullary region. She died of disease 8 months after surgery. Microscopically, the tumor was extensively necrotic. It was composed of islands and trabeculae irregularly infiltrating the muscular wall of the duodenum. Neoplastic cells were large and had a high mitotic index. Immunohistochemically, they expressed cytokeratin, chromogranin, synaptophysin, and neuron-specific enolase. Large cell neuroendocrine carcinoma is very rare in the ampulla of Vater, and it shares with its more common pulmonary counterpart the same morphology and probably the same poor prognosis.