[Clinicopathologic study on minute endocrine tumors of the pancreas--analysis of autopsy cases]

Using 800 autopsy cases (422 men, 378 women, mean age 78.7) mainly consisting of the aged, we made a clinicopathological analysis of endocrine tumors of the pancreas. The results were: 1) Endocrine tumors and similar lesions were found in 24 cases (25 lesions). 20 lesions (20 cases) were determined as tumors and five lesions (five cases) as hyperplasia of Langerhans islet. 2) Prevalence of tumor was 10% (6/60) in the all-section group and 1.6% (12/738) in the three-section group. Grossly observed tumor was in a single case. 3) As for the size of tumors, 35% of them were 1,000 microns or smaller. All of the five cases of hyperplastic lesions were 1,000 microns, or smaller in size. 4) None of the cases with tumors and hyperplastic lesions showed symptoms of excessive hormone. 5) In immunohistochemical analysis, hormone production was observed in all of the 20 cases of tumor and multiple hormone production was found in 14 of them (70%). 5) Ductular or tubular structures were found in or adjacent to tumor in 12 cases (60%) and hyperplasia in one case (20%). 6) One lesion each of tumor and hyperplasia were found in a single case. Langerhans islets, 500 microns or larger in size, were found in three lesions of tumor (15%). Furthermore, langerhans islets with the diameter of mean + 2 SD or larger were found around five lesions of tumor (25%) and three lesions of hyperplasia (60%). Above findings suggest that endocrine tumors of the pancreas is highly prevalent and most of them do not go beyond asymptomatic tumors (non-functional in the broad sense of meaning) with no symptoms of excessive hormone though they produce some hormones. And it is indicated that some of the endocrine tumors or hyperplasias develop from totipotent stem cells of duct epithelia, and factors that promote the growth of Langerhans islets might exist.