Operative indications for cystic lesions of the pancreas with malignant potential--our experience

There are still many important but unclear points regarding the differential diagnosis and operative indications of cystic lesions of the pancreas with malignant potential. Studies of the clinicopathological and molecular biological characteristics of such diseases are necessary. In this paper, we discuss operative indications for this condition based on a review of the literature and our own experience.

Seven cases of serous cystadenoma and 9 cases of mucinous cystadenoma or cystadenocarcinoma of the pancreas that were operated on or autopsied in our department from 1980 to 1996 were analyzed clinicopathologically. Small cystic lesions incidentally found in 300 autopsied cases were also studied. Finally, mucin-producing tumors described in several reports were reviewed, and the branch type of this tumor was especially investigated.

A marked disappearance of pancreatic acini in the upstream pancreas was found when serous cystadenoma became large. Papillary projection was histologically found in all of the cases. Tumorous invasion to the interstitium was suspected in tumors more than 5 cm in diameter, and malignancy was reported when tumors were larger than 6 cm. As for mucinous cystadenocarcinoma, the patients had a poor prognosis. In 2 of 42 cases with a pseudocyst, small duct cell carcinoma was incidentally found adjacent to the pseudocyst on the duodenal side. With regard to branch-type intraductal papillary neoplasm, 80% of the tumors larger than 4 cm were malignant. Most of the small cystic lesions found in elderly autopsy cases were accompanied by hyperplastic epithelia without evidence of malignancy.

Based on our experience, an operation should be considered and resection is recommended under the following circumstances: 1) cystic lesions in the body and tail of the pancreas in middle-aged women; 2) typical serous cystadenoma larger than 4 cm; 3) mucinous cystadenoma of any size; 4) branch-type intraductal papillary neoplasm larger than about 3 cm; and, 5) pseudocysts of unknown cause. Small cystic lesions in elderly patients should not necessarily be operated on, but should be followed-up carefully.