Mucinous cystic neoplasms of the pancreas with overt and latent malignancy (cystadenocarcinoma and cystadenoma). A clinicopathologic study of 41 cases.

Abstract

Forty-one cases of mucinous cystic neoplasms of the pancreas have been studied. They have traditionally been classified as cystadenoma or cystadenocarcinoma but have not been clearly distinguished from glycogen-rich, mucin-negative microcystic adenomas of the pancreas. Mucinous cystic neoplasms are usually large, often multilocular, usually form papillae lined with columnar, mucin-producing epithelium, and are found mainly in the body and tail of the pancreas. They occur chiefly in middle-aged women and are often discovered as an abdominal mass in association with local pain. Most of these neoplasms contain either adenocarcinoma or markedly atypical columnar epithelium. The authors’ data suggest that, given sufficient time, virtually all of these neoplasms will form foci histologically identifiable as carcinoma. Consequently, all “cystadenomas” are potentially malignant. Total excision is necessary. Internal drainage or partial excision ensures recurrence and possible metastasis. Within the same tumor it is common to find apparently benign epithelium as well as atypical or obviously malignant epithelium. Extensive sampling of the tumor by multiple histologic sections is often necessary to demonstrate the presence of carcinoma. Because of the large size of many of the neoplasms, the adequacy of sampling is difficult to assess. Thus, the authors doubt that a “benign” mucinous cystic neoplasm can always be separated from its malignant counterpart, and therefore they believe that all of these tumors should be regarded as either actually or potentially malignant.