Histochemical demonstration of mucins in the intramucosal laminated structure of human gastric signet ring cell carcinoma and its relation to submucosal invasion.

Thirty-one cases of signet ring cell carcinoma of the human stomach at an early stage were studied, employing a variety of histochemical techniques to characterize mucins and to elucidate factors accelerating the invasion of carcinoma beyond the muscularis mucosae. Signet ring cells were classified into six types largely depending on their histochemical reactivities. In 29 of 31 cases examined, the histochemical stainings detected the presence of characteristic mucins in an intramucosal laminated structure of proliferating carcinoma cells. The upper and lower layers of the typical intramucosal laminated structure consisted of carcinoma cells containing surface mucous cell and glandular epithelial cell-type mucins respectively, whereas the middle layer was occupied by immature carcinoma cells. Such a structure appeared to simulate cellular differentiations occurring in normal mucosa. The intramucosal laminated structure underwent structural distortion or disappeared, where submucosal invasion was evident. Ulceration appears to trigger the invasion beyond the muscularis mucosae.