Cholangiocarcinoma at the cystic duct discovered by lymph node metastases with clear cell transformation.

We encountered a case with cholangiocarcinoma of the cystic duct, which was first manifested by multiple lymph node metastases with clear cell changes resembling clear cell adenocarcinoma (CCC). Because the clear cell changes were not prominent at the primary site, clear cell transformation might have occurred preferentially at the metastatic lesion in this case. Alternatively, tumor cells with clear cell transformation, found at the primary site, might have high metastatic potential. The patient showed thromboembolism and hypercalcemia as paraneoplastic syndromes at the terminal stage as reported in patients with CCC of the ovary. Those complications might be common biological features of CCC.