Report on an Immunohistochemical and Ultrastructural Study of a Case of Solid and Cystic Tumor of the Pancreas

Naoto Maeda, Yutaka Horie, Hironaka Kawasaki and Haruhiko Yoshida*

Second Department of Internal Medicine and *First Department of Pathology, Faculty of Medicine, Tottori University, Yonago 683, Japan

In this report we studied a case of a solid and cystic tumor (SCT) of the pancreas in a 49-year-old woman. The tumor was located in the body and tail of the pancreas. The resected specimen revealed a firm, encapsulated mass with central necrosis and hemorrhage. Microscopically, the tumor consisted mainly of sheets of polygonal cells with papillary and pseudorosette structures. The tumor cells contained numerous PAS-positive and diastase-resistant granules in their cytoplasms. An immunohistochemical analysis showed a positive reaction for alpha-1-antitrypsin, but negative stains for insulin, glucagon, somatostatin and pancreatic polypeptide. Ultrastructurally, the tumor cells had numerous zymogen-like granules with desmosome on the cell membranes. No neurosecretory granules were found. These findings suggest acinar cell differentiation of SCT cells.

Key words: acinar differentiation; immunohistochemistry; pancreas; solid and cystic tumor; ultrastructure

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