Epithelial-mesenchymal interactions can influence the phenotype of carcinoma metastases in the mucosa of the intestine.

In this paper we report two cases in which morphological differentiation of gastric adenocarcinoma has occurred when metastatic tumour was present within the lamina propria of the intestinal mucosa. In one case, there were metastases in the small intestinal mucosa and in the second case, in the mucosa of the appendix. The morphology of the intramucosal tumour simulated that of an adenomatous neoplasm. The recognition of this occurrence may be important in the differential diagnosis of primary and secondary adenocarcinomas of the gastrointestinal tract. The phenomenon is not only of diagnostic interest: the data presented here provide in vivo evidence that gastrointestinal carcinomas may differentiate in response to epithelial-mesenchymal interactions in a similar way to that seen in experimental models.