RESUMO
A 47-year-old Japanese woman in whom obstructive jaundice had already been diagnosed, was found to have a dome-shaped elevated tumor approximately 3 cm in diameter located in the area very close to the papilla of Vater on endoscopical and radiographical investigations. Histopathologically, the resected tumor was composed mainly of solid nests of atypical argyrophilic cells, and partially of an area of well differentiated tubular adenocarcinoma, showing mutual transition in the mucosal layer. Both immunohistochemical and ultrastructural analyses confirmed the difference in character of tumor cells between these two areas: neuroendocrine cell carcinoma and tubular adenocarcinoma of common type in the intestine. To the best of our knowledge, this is only the third case reported to be a coexisting malignant carcinoid tumor and adenocarcinoma arising in the periampullary region.