A case of biliary cystadenocarcinoma of the liver.

We describe a case of biliary cystadenocarcinoma of the liver, a very rare malignant tumor, in a 40-year-old man referred to our hospital because of sporadic abdominal pain. A left lobectomy of the liver was performed, and macroscopic examination of the resected specimen revealed prominent papillary projections in a multiloculated cystic tumor containing mucinous material. Histologic examination of the specimen showed a biliary cystadenocarcinoma without mesenchymal stroma, associated with a cystadenoma. Cystadenoma with mesenchymal stroma (CMS), which occurs exclusively in women, is generally regarded as a precancerous lesion, and patients with biliary cystadenocarcinoma with mesenchymal stroma have a good prognosis. Cystadenoma without mesenchymal stroma arises in both men and women. However, the origin and precancerous lesions of cystadenocarcinoma are unknown. Moreover, the prognosis of patients with biliary cystadenocarcinoma without mesenchymal stroma is poor, especially in men. The cystadenoma without mesenchymal stroma in our patient was considered a precancerous lesion. The present patient has shown no evidence of recurrence in the 8 years after hepatic resection. Previously reported cases of cystadenocarcinoma without mesenchymal stroma, especially those in men, have had a poor outcome. A good outcome in men is very rare.