Published in Cancer Detection and Prevention 2000; 24(6):572-578.

Immunohistochemical Localization of Pancreatic Secretory Trypsin Inhibitor in Malignant Pancreatic Endocrine Tumors

Terumi Kamisawa, MD,a Yuyang Tu, MD,a Naoto Egawa, MD,a Jun -ichi Ishiwata, MD,a kouji Tsuruta, MD,b Atsutake Okamoto, MD,b Yukiko Hayashi, MT,c and Mono Koike, MDc

Departments of aInternal Medicine, bSurgery, and cPathology Tokyo Metropolitan Komagome Hospital, Tokyo, Japan

Address all correspondence to: Terumi Kamisawa, MD, Department of Internal Medicine, Tokyo Metropolitan Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 118677, Japan.

ABSTRACT: Differentiation of benign from malignant pancreatic endocrine tumors by existing clinical, biochemical, histologic, and cytologic criteria is difficult. We immunohistochemically localized pancreatic secretory trypsin inhibitor (PSTI) in 28 pancreatic endocrine tumors (13 benign, 15 malignant). PSTI-immunoreactive cells were detected in nine endocrine tumors. Immunoreactivity in these tumors was detected in nearly all tumor cells in five cases, scattered cells in two cases, and a few cells in two cases. All positive cases were malignant, and eight were equal to or larger than 10 cm. Serum concentrations of PSTI were markedly elevated in the two patients so tested. PSTI may be a specific immunohistochemical marker for malignant pancreatic endocrine tumors.

KEY WORDS: islet-cell tumor, tumor marker, immunohistochemistry, malignancy, functioning tumor.