Biliary cystadenocarcinoma: Case report of hepatic malignancy originating in benign cystadenoma.

A case of biliary cystadenoma undergoing malignant dedifferentiation is presented. Biliary cystadenocarcinoma is an infrequently occurring neoplasm; fewer than 20 cases have been reported in the literature. This case is the first in which there is documentation of cystadenocarcinoma arising from a previously diagnosed benign cystadenoma. Over a six-year period, the patient had three recurrences. The initial lesion and the first two recurrences were treated by drainage and biopsy. Histologically each succeeding specimens showed increasing atypia. Finally the majority of the lesion was excised, and microscopic examination revealed both benign and atypical epithelium and papillary adenocarcinoma, suggesting transition from benign to malignant. Thus, in view of the malignant potential of biliary cystadenomas, treatment of choice is total excision if surgically feasible.