True about Biliary cystic adenocarcinoma
Hepatic cystadenocarcinoma arising from pre-existing cystadenoma with mesenchymal stroma, which occurs only in young females, carries good prognosis resection is the treatment it carries a good prognosis. MRI is diagnostic. 
US/CT scan is also helpful. ERCP is done to identify communication with the biliary system usually to proximal left hepatic duct.
CT scan is used for diagnosis
CA 19-9 is elevated
intrahepatic location
Extrahepatic location