Abstract
One feature of Intraductal Papillary-Mucinous Tumors (IPMT) is the production of a large amount of mucin. The hyperplasia-adenoma-carcinoma sequence is suggested as the carcinogenic mechanism. In this study, we classified 28 IPMT cases into four groups and examined the proliferative potential, the mucin producing potential, and molecular biological characteristics. In addition, we examined the immunohistochemical characteristics of mucin. It was shown that the malignant potential rose in proportion to indices for the prolif erative potential, Mitotic Index, PCNA, and Ki-67-LI (Labeling Index) . We examined the mucin producing potential of IPMT, which shows multiple graded malignancy. Groups I and II, which showed a lower grade of malignancy, produced large amounts of mucin mainly consisting of neutral glicoprotein, the proliferative potential rose, while the producing potential cell. As the proliferative potential became higher the tumor acquired the potential for producing large amounts of mucin again, and the main constituent of mucin changed to acid mucopolysaccharides. In groups III and IV, MUC-l positive cells appeared. We thought the tumor cells acquired an invasive potential, and the malignant grade rose at this phase.
