Adenoendocrine cell carcinoma of the gallbladder: a histochemical and immunohistochemical study.

A case of adenoendocrine cell carcinoma of the gallbladder with adenomucous cells and neuroendocrine cells is reported. A histochemical and immunohistochemical study revealed that the primary tumor in the gallbladder was composed of mucus-secreting and/or argyrophil cells. Furthermore, the tumor showed a positive reaction to carcinoembryonic antigen (CEA) in all tumor cells, to chromogranin A and cytokeratin in many tumor cells, to endocrine granule constituent (EGC) in some tumor cells, and to serotonin and somatostatin in a few tumor cells. In addition, a few mucous cells showed argyrophilia and EGC-positivity in their cytoplasms. This case suggests that the adenoendocrine cell tumor is derived from endodermal stem cells as a result of bidirectional (exocrine and endocrine) differentiation.