Adenoacanthoma of the pancreas: report of four cases and literature review.

Cases of 20 patients with adenoacenthoma of the pancreas with clinicopathologic data, including the four added, are reviewed. The clinical manifestations, sites of metastases, survival and gross pathology appear to be similar to the usual adenocarcinoma of the pancreas. Adenoacanthoma of the pancreas most probably represents squamous metaplasia of an adenocarcinoma or arises from an undifferentiated cell in the pancreatic duct system. The metastases are typically an admixture of both elements but in four cases, pure squamous or adenocarcinoma metastases were encountered. It is suggested that the pancreas should be included as a possible source in those patients with an unknown primary who have a metastasis consisting of either an admixture of squamous and glandular elements or a pure squamous type and in those instances in which a pure squamous and a pure adenocarcinoma are encountered in different metastases.