Gastric carcinoma with argyrophilic cells: light microscopic, electron microscopic, and immunochemical study.

An immunochemical study of a gastric adenocarcinoma with argyrophilic cells showed two areas of tumor that react differently with the usual histochemical reagents as well as with immune sera against gastrin and mucoprotein associated with antigens. Ninety per cent of the tumor cells were PAS positive and contained M2 antigen, and some also contained M1 antigen. About 30 per cent of the M2-positive cells stained strongly with an antigastrin serum as well as with the argyrophilic reagents. The remaining 10 per cent of tumor cells were signet-ring cells located in several clumps in the tumor. These cells were positive for both PAS and alcian blue and contained intestinal M3 antigen. Forty-five per cent of them also contained M1 gastric antigens. Carcinoembryonic antigen (CEA) was found in the cytoplasm of each tumor cell. The presence of CEA and M1 antigen together indicates a fetal pattern, suggesting that the cells originate from very immature gastrointestinal stem cells.