Intrahepatic cystadenocarcinoma with pleural dissemination: a case report.

A 40-year-old Japanese woman, who previously had undergone choledocho-jejunostomy in childhood for a congenital choledocal cyst, presented with right-sided chest pain. Computed tomography and ultrasonography demonstrated a right pleural effusion and a 10-cm unilocular hepatic cystic lesion with no solid component. These findings suggested a non-neoplastic cyst or cystadenoma. However, intracystic fluid aspirated had high concentrations of carbohydrate antigen 19-9 and carcinoembryonic antigen. Cytology of the pleural effusion demonstrated malignant cells. During exploratory laparo- and thoracotomy, a hepatic cystadenocarcinoma with invasion of the diaphragm and pleural dissemination was discovered. This case demonstrates that malignancy should be ruled out when a patient with an intrahepatic unilocular cystic lesion presents with atypical symptoms and findings, such as chest pain, pleural effusion, and high serum concentration of tumor markers. We believe that intrahepatic cystic lesions should be approached aggressively, including the use of exploratory laparotomy/laparoscopy to be certain that cancer is not present.