Fig. 4

Colonic adenocarcinoma. Epithelial predominant (epithelial phenotype) colonic adenocarcinoma (a and b). Hematoxylin and eosin stained section (a) and corresponding RNA in situ hybridization stain (b) showing tumor cells exclusively expressing epithelial markers. Mesenchymal gain (quasimesenchymal phenotype) (c and d). The tumor cells show both epithelial markers (*) and mesenchymal markers (arrow) (d). The mesenchymal markers were often expressed at the periphery of tumor islands. Colonic adenocarcinoma with near-exclusive mesenchymal phenotype (e and f). Although most of the tumor shows loss of epithelial and gain of mesenchymal markers, rare foci of tumor (arrow) showed only paucity of epithelial markers. a, c, and e—hematoxylin and eosin stain. b, d, and f—in situ hybridization stain for epithelial and mesenchymal markers