Serotonin in tubular adenomas, adenocarcinomas and endocrine tumours of the stomach

Serotonin was examined immunohistochemically in seven tubular adenomas, 194 adenocarcinomas and 41 endocrine cell tumours of the stomach. In tubular adenomas, serotonin-containing cells showing argentaffinity were present in the lower portion of the adenomatous glands and were considered to be an expression of intestinal character. Scattered serotonin-containing tumour cells were found in 60 (30.9%) of 194 adenocarcinomas regardless of their histological type. Cell fusions between carcinoma and enterochromaffin (EC) cells might be a possible mechanism for the occurrence of serotonin-containing cells within the tumour. In 17 (54.8%) of 31 endocrine cell carcinomas, serotonin-containing tumour cells were observed in a variable degree in contrast to the absence of these cells in classical carcinoid. Moreover, diffuse serotonin reactivity was found in four cases of scirrhous endocrine cell carcinoma. The histogenesis and the occurrence of serotonin-containing cells in each type of gastric tumour is also discussed.