A case of AFP-positive pancreas papillary carcinoma suggestive of a primitive endoderm phenotype.

In a 70 year old woman with a tumor in the head of the pancreas, the lesion was predominantly composed of papillary adenocarcinoma protruding into the main pancreatic duct, with periductal invasion. The major portion of the adenocarcinoma was intraductal and was composed of tall columnar epithelial cells with pseudostratified nuclei, had the appearance of primitive endodermal epithelium and was positive for carcino-embryonic antigen. In contrast, in the other portion of the adenocarcinoma which had the predominant component of periductal invasion, neoplastic cells had an irregular, eosinophilic cytoplasm, resembled ordinary pancreas adenocarcinoma of ductal origin and was positive for CA19-9. Neuro-endocrine and alpha-fetoprotein-positive cells with a primitive appearance were scattered among the neoplastic epithelial linings. In addition, a vimentin-positive sarcomatoid component intermingled with the adenocarcinoma. These findings suggest that the adenocarcinoma observed in this tumor with the primitive appearance also had a primitive phenotype. This was evidenced by immunohistochemistry and the divergent directions of differentiation. This particular case illustrates that pancreas adenocarcinoma of the ordinary histologic type can arise secondarily from the more primitive neoplastic cells during carcinogenesis within the pancreatic duct.