Histamine in gastric carcinoid tumors: Immunocytochemical evidence.

Gastric carcinoid tumors and nontumorous corpus mucosa from 4 patients suffering from chronic atrophic gastritis associated with pernicious anemia were characterized histochemically, with special reference to the cellular localization of histamine. Tissue sections were also examined for argentaffinity using the Masson technique, for argyrophilia using the Grimelius and Sevier-Munger techniques, and for chromogranin A and serotonin immunoreactivities. The majority of the tumor cells showed the staining characteristics of enterochromaffinlike cells: That is, they exhibited the argyrophil reaction with the Grimelius and Sevier-Munger techniques but lack of argentaffinity, positive histamine and chromogranin A immunostaining, but no serotonin immunoreactivity. Numerous histamine-immunoreactive mast cells were present in the stroma of the tumors and also in the surrounding mucosa. Our findings support the view that gastric carcinoids in patients with hypergastrinemia due to chronic atrophic gastritis are histamine-producing tumors derived from hyperplastic enterochromaffinlike cells.