One hundred four endocrine
tumors found in the body and tail of the pancreas of a patient with the
Zollinger-Ellison syndrome (ZES) and
multiple endocrine neoplasia (MEN-I) were investigated by immunohistochemistry for
insulin,
glucagon,
somatostatin,
pancreatic polypeptide (PP), and
gastrin. The results for each
tumor were scored into six grades according to the frequency of immunoreactive cells.
Pancreatic polypeptide,
glucagon,
insulin, and
somatostatin were demonstrated in 96, 80, 62, and 42
tumors, respectively. When only the higher scores of cell frequency (3-5) were considered, PP and
glucagon (accounting for 71 and 49
tumors, respectively) differed markedly from
insulin (two
tumors) and
somatostatin (0). The frequency of PP-immunoreactive cells was higher in
tumors of large size whereas that of
glucagon cells was higher in the smaller
neoplasms. No significant associations of the tumoral hormonal expressions were found with the type of histologic structure (trabecular versus gyriform), the occurrence of stromal
fibrosis, and the intrapancreatic location of the
neoplasms, except for a higher number of somatostatin cells in fibrotic
tumors.
Gastrin-immunoreactive cells never were found in the
tumors in spite of the concomitant hypergastrinemia. In conclusion, the nonrandom expression of the hormonal phenotype by the neoplastic islet cells, as shown by the immunohistochemical, semiquantitative analysis of a large number of
tumors, suggests that in our MEN-I patient the genetically determined
neoplasms also are affected by other mechanisms, possibly nongenetic.