Unusual Proliferation or the Pancreatic Endocrine Cells in Adults, Suggestive of Islet Cell Metaplasia

We present two adult autopsy cases with malignancy, in which unusual proliferation of the pancreatic endocrine cells was observed. Histopathological examination revealed extensive proliferation of the pancreatic endocrine cells throughout the pancreata in both cases. The islets of the pancreas were enlarged with irregular contours. An admixture of the islet cells, acinar cells and ductular epithelial cells was also observed. Immunohistochemically, these islets were composed of the endocrine cells of various types, i.e. A-, B-, D- and PP-cells, and they showed a predominance of PP-cells. Clinically, endocrine hyperfunction of the pancreas was not detected in either cases. Although this histological change may be described as endocrine cell hyperplasia or dysplasia, the close connection of the islet cells, acinar cells and ductular epithelial cells might rather suggest metaplastic change of the acinar or ductular cells into the islet cells under unknown stimuli.