Morphogenesis of peritoneal metastasis in human gastric cancer.

A comparative light microscopic and scanning electron microscopic study of the morphogenesis of peritoneal metastasis in 34 human gastric cancers was performed. Prior to adhesion of gastric cancer cells to the peritoneum, the mesothelial cells became hemispherical and exfoliated from the peritoneum, and gastric cancer cells adhered to the naked areas of the submesothelial connective tissue. A flat metastatic tumor was formed by cancer cell proliferation in the shallow region of the peritoneum. Subsequently, after the infiltration of cancer cells into the connective and adipose tissue, the formation of a large tumor mass was observed. There was a correlation between the surface and histological structure of the metastatic tumors. In poorly differentiated cancer, the cells were isolated while in differentiated cancer, they formed nodules with indistinguishable cell boundaries.