Intraductal Papillary-Mucinous Neoplasms of the Gastric and Intestinal Types May Have Less Malignant Potential Than the Pancreatobiliary Type

Objectives: Intraductal papillary-mucinous neoplasms (IPMNs) of the pancreas are classified into 4 types-gastric, intestinal, pancreatobiliary, and oncocytic-on the basis of their morphology and immunohistochemistry. We classified IPMNs at our institute and used this classification to determine the clinicopathological features, prognosis, and malignant potential of the 4 types. Methods: Sixty-one patients with IPMN who underwent surgery between 2000 and 2007 were evaluated retrospectively. Results: There were 24 tumors of the gastric type, 22 intestinal, 12 pancreatobiliary, and 3 oncocytic. Patients with the intestinal or gastric type had a better prognosis than those with the pancreatobiliary type. The intestinal and pancreatobiliary types had almost the same frequencies of carcinoma, but the intestinal type tended to have a lower frequency of invasive carcinoma than the pancreatobiliary type. Patients with invasive carcinomas derived from intestinal-type IPMNs tended to have a better prognosis than those whose invasive carcinomas were derived from the pancreatobiliary type. Conclusions: Intraductal papillary-mucinous neoplasm of the gastric and intestinal types may have less malignant potential than that of the pancreatobiliary type. Invasive carcinomas derived from intestinal-type IPMNs may be less invasive and slower growing than those derived from the pancreatobiliary type.