An immunohistochemical and ultrastructural study of case of small-cell neuroendocrine carcinoma in the ampullary region of the duodenum.

One case of small-cell neuroendocrine carcinoma in the ampullary region of the duodenum is reported. The histological appearance of the tumor was identical to pulmonary small-cell carcinoma. Neuroendocrine differentiation was demonstrated immunohistochemically by positive immunoreaction for neuron specific enolase, Leu-7 and chromogranin, and ultrastructurally by the presence of scanty dense-core neurosecretory type granules. Small-cell neuroendocrine carcinoma in the ampulla of Vater is extremely rare. To our knowledge, this is the sixth reported case.