Immunohistochemical and Ultrastructural Cellular Differentiation in Papillary and Solid Epithelial Neoplasm of the Pancreas

ABSTRACT

Papillary and solid epithelial neoplasm of the pancreas from five patients were studied using immunohistochemistry and electron microscopy to define the cellular origin of this type of tumor. The tumors ranged in diameter form 5.5 to 15 cm Grossly, these were well circumscribed by a firm, gray-white, fibrous capsule and their cut-surface showed mainly area containing mucinous substance with necrotic and hemorrhagic material, with some solid portion. Microscopically, there was a solid and papillary pattern, with uniform cells typically having round to ovoid nuclei containing indistinct nucleoli and eosinophilic, granular cytoplasm. Within the cytoplasm of the tumor cells, numerous PAS-positive granules were found. Immunostaining was positive for neuron-specific enolase(three of five cases), alpha1-antitrypsin and alpha1-antichymotrypsin(three of five cases) in the solid and papillary portion of the tumor. But no polypeptide hormone immunoreactive cells were present in all cases except for gastrin which showed focally weak positivity in the papillary area. Ultrastructurally, the papillary and solid epithelial neopasm of the pancreas showed evidence of acinar cell differentiation, because in the cell of one observed some zymogen-like granules and presence of annulate lamellae. But also, abundant typical neurosecretory granules were detected in the tumor cells ultrastructurally. Both facts suggested acinar and islet cell differentiation of the tumor. From the these findings, it concluded that papillary and solid epithelial neoplasm of the pancreas may be originated from a primordial cell which will be able to render both endocrine and exocine component.