Background: In 1989, Morohoshi et al. reported an intraductal papillary neoplasm of the pancreas (IPNP), which was a morphologically distinct, but rare tumor.
Methods: Two cases with IPNP were analyzed by immunohistochemical and DNA flow cytometric methods.
Results: The patients included a 67-year-old man and a 71-year-old woman. Both tumors were characterized by a well-defined papillary growth in the cystically dilated main pancreatic ducts, associated with papillary and nonpapillary hyperplasia. Immunohistochemically, the tumor cells of both cases were positive for the epithelial markers (AE1/AE3 and CAM 5.2), and in one of the two cases, the tumor cells and hyperplastic cells surrounding the tumor conspicuously revealed multiple hormonal markers such as serotonin, somatostatin, glucagon, gastrin, and pancreatic polypeptide. The nuclear DNA content of the tumor cells of the first case, which showed moderate cellular atypia, was considered to be diploid, whereas that of the second case, which revealed severe atypia, was aneuploid.
Conclusions: These results suggested that these tumors arose from multipotential stem cells capable of epithelial and neuroendocrine differentiation, and results of the flow cytometric study was related to the degree of cellular atypia of the tumors.