A Case of Adeno-endocrine Cell Carcinoma of the Gallbladder

Endocrine cell tumors occur in the rectum, stomach, and appendix, but primary endocrine cell carcinoma of the gallbladder is rare. We encountered a rare case of adeno-endocrine cell carcinoma of the gallbladder in a 72-year-old man. The nodular protruded tumor (252×20×20mm) was found in the fundus. Direct invasion of the liver bed, lymph node metastasis, and liver metastasis were seen. Histologically, the tumor consisted of two components, well-differentiated adenocarcinoma and endocrine cell carcinoma. The tumor cells in the area of the endocrine cell carcinoma were small and round-shaped. The nuclei were irregular in size and exhibited severe atypia and hyperchromatism. The tumor cells were arranged in irregular nests and a trabecular structure, and almost all of them showed a positive argyrophil reaction in the cytoplasm. A diagnosis of adeno-endocrine cell carcinoma was made. A transition between both histological features was seen histologically. It was suggested that the histogenesis of endocrine cell carcinoma of the gallbladder is closely related to that of adenocarcinoma.