Immunohistochemical study of the distribution of pancreastatin in endocrine tumors of the pancreas and in normal pancreatic tissue: analysis of autopsy cases.

Using sixteen cases (sixteen lesions) of endocrine tumor of the pancreas, found in 1,300 consecutive autopsy cases (661 men and 639 women; mean age, 79.0 years), we examined distribution patterns of pancreastatin (PST) in these endocrine tumors and in normal tissues around them, using immunohistochemical staining. In addition, the distribution patterns of PST was compared with those of insulin (INS), glucagon (GLU), somatostatin (SOM), and pancreatic polypeptide (PP), in these tissues. Normal islets of Langerhans were stained completely and evenly for PST. Two endocrine tumors did not stain for PST at all, six were partially stained, and eight were stained as densely as normal islets, or even more densely. Acinar cells were only partially stained for PST in 11 cases and showed scattered staining in three cases. Epithelial cells of ducts or ductuli were partially stained for PST in 10 cases and showed scattered staining in three cases. Distribution patterns of PST coincided with that of INS in 56% (9/16) of cases, GLU in 81% (13/16), SOM in 31% (5/16), and PP in 31% (5/16). In the eight tumors that were stained at least as densely for PST as normal islets, the staining pattern did not coincide with that of INS in any case (0%), coincided with that of GLU in all 8 cases (100%), and coincided with those of SOM and PP in one case each (13%). Therefore, the distribution of GLU-producing cells (A cells) coincided most closely with that of PST. It is concluded that most PST is secreted from A cells in human pancreas.