A Case of Biliary Cystadenocarcinoma Which Showed an Interesting Change of Shape in the Radiographic Appearance

In August 1997, abdominal ultrasonography during a physical examination of a 55-year-old female revealed a unilocular cyst measuring 8 cm in the medial segment. Abdominal computed tomography (CT) showed a low absorption unilocular cyst with a smooth inner wall and flat lumen. On October 27, 1998, the patient consulted our department for back pain. Abdominal ultrasonography revealed a small cyst measuring 2.5 cm within the cyst. Abdominal CT showed papillary swelling on the cystic wall, which protruded into the lumen. CT arteriography showed irregular swelling involving the cystic wall and cystic lumen as well as the small cyst. A preoperative diagnosis of hepatic cystoadenocarcinoma was made, and partial resection of the medial hepatic segment was performed. The resected specimen revealed microcysts in addition to the small cyst in the cystic wall. Histopathological examination showed that the entire cystic wall and the wall of the small cyst consisted of cancer tissue, and that the inner wall of the microcysts consisted of adenoma. Hepatic cystic adenoma may have caused the hepatic cystadenocarcinoma in this patient. In addition, the morphological chagnes in the cyst observed during follow-up were considered to be related to cancer cell proliferation.