Intraductal papillary‐mucinous neoplasms of the pancreas

BACKGROUND: Intraductal papillary-mucinous neoplasms (IPMNs) of the pancreas are intraductal tumors with variable amounts of papilla formation, mucin production, and cytoarchitectural atypia. Associated invasive carcinomas, reported to occur in up to 30% of patients, often are mucinous and clinically indolent. METHODS: The clinical and pathologic features of 28 IPMNs resected at Memorial Sloan-Kettering Cancer Center between 1983 and 1997 were reviewed. RESULTS: There were 16 females and 12 males with a mean age of 68 years (range, 44-79 years) and a mean tumor size of 4.5 cm (range, 1.5-11.0 cm). The head of the gland was the predominant tumor site (89%). Abdominal pain, weight loss, and acholic stool were the most common symptoms at presentation. According to histology, two types of papillae were identified: intestinal (22 patients) and pancreatobiliary (6 patients). In the intraductal component, cytologic atypia was minimal (i.e., intraductal papillary-mucinous IPM adenoma) in 2 patients and moderate (IPM borderline tumor) in 5 patients, and severe atypia (IPM carcinoma in situ) was seen at least focally in 21 patients. In addition, invasive carcinoma was identified in 15 patients (53%), 4 of whom had only microscopic foci. Invasive carcinoma was of the mucinous type (colloid) in six patients and of the tubular type (conventional ductal adenocarcinoma) in nine patients. At a median follow-up of 35 months, four patients died of disease; two of these patients had only borderline atypia with no identified in situ or invasive carcinoma in the sections submitted. Eighteen patients had no evidence of disease, 1 patient was alive with recurrent disease, and 5 patients died of other causes. The actuarial 5-year disease free survival rate was 78%. Of the 14 patients with invasive carcinoma, 5 of 6 patients with colloid type tumors were free of tumor at a mean of 55 months. Of the patients with tubular type invasive carcinoma, two patients died of their disease (at 4 years and 7 years), three patients died of other causes, and four patients were alive (three were free of disease, and one experienced disease recurrence) at an average follow-up of 7.5 years. CONCLUSIONS: Two distinct patterns of intraductal papillae are seen in patients with IPMNs: intestinal and pancreatobiliary. Both in situ and invasive carcinoma may be encountered more commonly than previously recognized. Tubular type invasive carcinomas occur as well as mucinous type (colloid) carcinomas. Although the neoplasms are less aggressive as a group than conventional pancreatic ductal adenocarcinoma, patients with IPMNs may pursue a deadly course, even in the absence of identifiable invasive carcinoma. Conversely, patients with tubular type invasive carcinoma arising in the background of IPMN may follow a more favorable course than patients with conventional ductal adenocarcinoma without IPMN, emphasizing the importance of recognizing the IPMN component in patients with pancreatic adenocarcinoma.