Cystic neoplasms of the pancreas.

Cystic neoplasms of the pancreas, including 4 patients with serous cystadenoma and 11 with mucinous cystic neoplasm, were studied. Serous cystadenomas composed of epithelial cells with glycogen in the cytoplasm were benign in all, whereas mucinous cystic neoplasms consisted of four benign, two borderline, and five malignant lesions. The average size was 1.8 cm in the greatest diameter in benign mucinous cystadenomas, about 5 cm in borderline tumors, and more than 8 cm in mucinous cystadenocarcinomas. Histologically, in all borderline and malignant lesions, the cysts contained areas lined with epithelium and had a benign appearance, comparable with that of mucinous cystadenoma. These observations suggest a borderline or malignant disease in the case of a benign mucinous cystadenoma. An immunohistochemical study for carcinoembryonic antigen and carbohydrate antigen 19-9 showed denser and diffuse localizations of such materials in the cytoplasm and the stroma in the case of malignant lesions, as compared to findings in borderline and benign cases.