OBJECTIVETo study the clinicopathologic features of intraductal papillary mucinous neoplasm (IPMN) and its distinction from mucinous cystic neoplasm of pancreas.

METHODSThe clinical, radiologic and histologic features of 17 cases of IPMN and 13 cases of mucinous cystic neoplasm (MCN) were reviewed. Mucin profiles (MUC1, MUC2 and MUC5AC) were studied by histology (HE) and immunohistochemistry (EnVision).

RESULTS10 of the 17 cases of IPMN were males. 13 cases of the IPMN were located in head of pancreas. Communication with the main pancreatic duct was demonstrated in 15 cases. Histologically, there were mild to severe papillary ingrowths of dysplastic epithelial cells, associated with intervening normal or atrophic pancreatic parenchyma. Ovarian-like stroma was not seen. Ancillary investigations showed that MUC2 and MUC5AC were detected in tumor cells of 9 and 4 cases respectively. The 4 cases with invasive component showed MUC1 positivity. On the other hand, 11 of the 13 cases of MCN occurred in middle-aged to elderly females and were located in the body and tail of pancreas. Ovarian-like stroma was commonly seen and there was no connection with the main pancreatic duct. All non-invasive MCN, regardless of the degree of cytologic atypia, were positive for MUC5AC (but not MUC2). In the 2 cases with invasive component, MUC1 expression was observed, as in IPMN.

CONCLUSIONSThe age and sex of patients, tumor location, absence of ovarian-like stroma, communication with main pancreatic duct and characteristic mucin profiles represent useful parameters in distinguishing IPMN from MCN of pancreas. The tumor cells of IPMN express mainly MUC2, while those of MCN express MUC5AC. MUC1 may also be a useful marker in demonstration of stromal invasion in these tumors.