[Intraductal papillary mucinous neoplasm of pancreas: a clinicopathologic and immunohistochemical study of 19 cases].

Objective: To study the clinicopathologic features and diagnosis of intraductal papillary mucinous neoplasm (IPMN) of the pancreas.

Methods: Nineteen cases of IPMN encountered during the period from 1999 to 2007 were studied by light microscopy and immunohistochemistry.

Results: IPMN occurred more often in males (68%). It affected patients in older age group (mean age = 59) and was located mainly in the head of pancreas (60%). The mean tumor size was 4.2 cm (range = 1 to 8 cm). The clinical presentation was epigastric pain (53%), weight loss (32%), diabetes (21%), pancreatitis (21%) and jaundice (10%). Pancreatectomy was performed in 18 cases. The remaining patient received bypass surgery only. Features of in-situ or invasive malignancy were present in 15 of the 19 cases (78%). Histologically, the tumor consisted of papillary proliferations protruding into and expanding the pancreatic ducts. Invasion into the surrounding pancreatic parenchyma was noted in 12 cases and chronic pancreatitis was present in 16 cases. Follow-up data (4 to 48 months) were available in 13 patients. Apart from 1 patient who died of other disease, all were still alive. Immunohistochemical study showed that p53 was positive in 6 cases, p16 in 5 cases and fascin in 8 cases. The expression of c-erbB-2 was all negative. Ki-67 index ranged from 1% to 80% (mean = 38%).

Conclusions: Malignant changes are not uncommon in IPMN. The prognosis after surgical resection however is better than that of conventional pancreatic adenocarcinoma. The overexpression of p53, p16 and fascin may be related to tumor progression. The possibility of malignant transformation needs to be considered if the Ki-67 index is over 15%. Early recognition by radiologic examination (including ERCP) and pancreatic cytology would be helpful in early diagnosis. Surgical resection represents the mainstay of treatment and long-term post-operative follow up is needed.