Squamous metaplasia with reserve cell hyperplasia in the esophagogastric junction zone.

The entire mucosa of the esophagogastric junction zone (E.G.J.) was examined histologically in 63 cases of total gastrectomy and 47 cases of esophageal resection. The squamocolumnar junction in E.G.J. was classified into three types, 1. Clear-cut demarcation type was found in 21 (19%) out of the total 110 cases, 2. Subepithelial inclusions of ectopic gastric epithelium type in 81 (74%) out of 110 cases, and 3. Barrett esophagus type in 8 (7%) out of 110 cases. By the primary disease, 4 out of 8 cases of type 3 were found in the cases of esophageal ulcer, and 4 were present in the cases of esophageal cancer. The mucosa of E.G.J. showed a squamous metaplasia with reserve cell hyperplasia as in the cervix uteri. The reserve cell hyperplasia was observed in 26(24%) out of 110 cases, and there were two cases which showed atypical change and nodular proliferation. The reserve cell hyperplasia and its atypical change were considered to be one of the sites for the development of squamous cell carcinoma in the junction zone. It was suggested that the primary site of squamous cell carcinoma in E.G.J. was not limited to the esophageal flat stratified squamous epithelium.