Background: Intraductal mucin-hypersecreting neoplasm of the pancreas (IMHN) is a unique tumor that has a tendency to spread intraductally. The clinical outcome of IMHN generally is far better than that of pancreatic ductal cell carcinoma. Because of the presence of various cell atypia within the same tumor, it sometimes is difficult to make an accurate histopathologic diagnosis and, therefore, predict its biologic behavior. It has been shown that overexpression of c-erbB-2 protein in breast cancer with lymph node metastases is related to a poor prognosis. Overexpression of c-erbB-2 protein has been reported as an infrequent event in pancreatic ductal cell carcinoma, but little is known in the case of IMHN.
Methods: The expression of c-erbB-2 protein was immunohistochemically investigated in the formaldehyde-fixed, paraffin-embedded tissues of 17 cases of IMHN, and 14 cases of pancreatic ductal cell carcinoma (8 cases with lymph node metastasis), using polyclonal and monoclonal c-erbB-2(p185) antibodies by the avidin-biotin method.
Results: Both the polyclonal and monoclonal antibodies showed similar immunostaining for the c-erbB-2 product. Overexpression of the c-erbB-2 product was observed frequently in IMHN (13/17), especially in that with moderate- to high-grade cell atypia (12/12), whereas it was detected in only 1 of 14 cases of pancreatic ductal cell carcinoma (1/14). Among eight cases of pancreatic ductal cell carcinoma with lymph node metastases, overexpression of the c-erbB-2 product in metastatic lesions was detected in two, one of whose primary lesions also overexpressed the oncogene product.
Conclusions: These observations suggest the genetic expression of c-erbB-2 is related to the pathogenesis of IMHN.