Two cases of multiple
islet cell tumors mostly composed of
glucagon-producing cells and associated with severe
ulcer disease are presented.
Multiple endocrine neoplasia type I (MEN-I) was present in both patients, although symptomatically latent in case 2. Immunohistochemistry showed that
glucagon (A) cells were a major cell population (i.e., accounting for at least 30% of the
tumor cell population) in 24 of 43
tumors (either macroadenomas or microadenomas) studied in case 1 and in 12 of 17
tumors studied in case 2. A major
pancreatic polypeptide (PP) cell population was found in 12 and 7
tumors of case 1 and 2, respectively. In contrast,
insulin (B) and
somatostatin (D) cells were scarce in most
adenomas.
Gastrin-producing cells were not identified in any
tumors, despite the use of different
antigastrin antisera. Extrapancreatic or residual
gastrinomas were not found at postmortem examination in case 1 or on appropriate surgical inspection done 24 years after the onset of the
ulcer disease in patient 2. On the basis of these and of 17 additional cases collected in the literature, it is concluded that multiple A-cell
tumors of the pancreas are an expression of the MEN-I and are mostly associated with
ulcer disease and/or with hypergastrinemia of frequent uncertain origin. The mechanisms regulating the nonrandom phenotypic hormonal differentiation of these genetically determined
tumors remain unknown.