Intraepithelial mast cells in the human gastric mucosa in a case of microcarcinoidosis.

A 63-year-old female patient with pernicious anaemia and chronic transformation-gastritis with numerous disseminated endocrine cells of the fundus glands had developed a diffuse microcarcinoidosis. Mast cells were identified not only in the stratum proprium mucosae, but also in the epithelium of atypical glands of the basal mucosa. Electron and light microscopic investigations clearly showed that the intraepithelial mast cells emigrated into the neighbouring stroma. During the process of secretion the ultrastructure of the specific granules changes continuously, whereby four different phases can be distinguished by the electron microscope.