Intraductal papillary-mucinous neoplasm of the pancreas. A clinicopathologic entity

The main clinicomorphologic findings from two new cases of intraductal papillary-mucinous neoplasm of the pancreas were analyzed and discussed.

Formalin-fixed pancreatic tissues from the more representative areas were routinely stained. An electron microscopic examination was performed in case 2 on glutaraldehyde-fixed tissue fragments.

Both patients had a long history of symptoms that was suggestive of chronic pancreatitis. At endoscopic retrograde pancreatography a dilatation of the main duct was observed. Ultrasonography revealed cystic dilatations that were interpreted as pseudocysts. The patients underwent total pancreatectomy. The gross appearance showed no mass, but the pancreas was enlarged and diffusely hard. The cut surface showed micromacrocysts filled with soft friable tissue and mucus. Histological examination revealed diffuse neoplastic papillary proliferations within ectatic and cystically dilated ducts. The lesions exhibited varying grades of atypia and foci of in situ carcinoma. No clear evidence of invasion or lymph node metastases were observed. The nontumorous pancreas showed diffuse and multiple hyperplastic papillary changes in the ductal tree.

The main clinicopathologic findings of intraductal papillary-mucinous neoplasm of the pancreas have been reported. Our study favors the hypothesis that chronic pancreatitis and/or ductal epithelial papillary hyperplasia may play a role in the pathogenesis of this tumor. We have emphasized the cystic appearance and mucinous features of this neoplasm, and so we suggest the use of the term intraductal papillary-mucinous neoplasm.