CELLULAR COMPOSITION AND ANATOMIC DISTRIBUTION IN NONFUNCTIONING PANCREATIC ENDOCRINE TUMORS - IMMUNOHISTOCHEMICAL STUDY OF 30 CASES

Objective To investigate the cytological pattern and distribution in n onfunctioning pancreatic endocrine tumors. Methods Using labeled strep tavidin-biotin (LSAB), immunohistochemical staining for insulin, gluca gon, somatostatin, pancreatic polypeptide and gastrin was performed on 30 nonfunctioning pancreatic endocrine tumors from 30 patients. The c ellular composition and anatomic distribution in these tumors were ana lyzed. Results Of 30 tumor tissues, 22 (73.3%) were found to contain c ells immunoreactive to 1-4 kinds of peptide hormones; 17 (56.7%) showe d positive staining for more than one peptide and up to 4 peptides; an d 8 (26.7%) showed negative immunoreaction to all antiserum applied. N o tumor: was found to contain immunoreactive gastrin. Among 17 multiho rmonal tumors, 4 contained 2 kinds of peptide hormones, 8 had 3 kinds, and 5 harbored 4 kinds of peptide hormones. In addition, the differen ce in the number and type of positive endocrine cells between the tumo rs arising from the head of the pancreas and those arising from the bo dy and tail of the pancreas were statistically significant (P<0.05). C onclusions Immunohistochemically, the high positive rate to peptide ho rmones suggests that the nonfunctioning pancreatic endocrine tumors ar e actually not nonfunctioning; they are asymptomatic pancreatic endocr ine tumors. Moreover, an uneven distribution of positive endocrine cel ls in the nonfunctioning pancreas endocrine tumors within the pancreas was identified.