Immunoreactivity of cytokeratins (CK7, CK20) and mucin peptide core antigens (MUC1, MUC2, MUC5AC) in adenocarcinomas, normal and metaplastic tissues of the distal oesophagus, oesophago-gastric junction and proximal stomach

Aims: Adenocarcinomas of the distal oesophagus and especially the oesophago-gastric junction have shown an increasing incidence during the last decade. Definition of subgroups according to different sites of development, histogenesis or aetiology may prove to be valuable for clinical diagnosis and treatment. Previous studies have shown differences in cytokeratin patterns between Barrett's metaplasia of the oesophagus and intestinal metaplasia in the stomach. The aim of our study was to investigate whether the expression of certain cytokeratins (CK7, CK20) and mucins (MUC1, MUC2, MUC5AC) exhibit clear-cut patterns, thus allowing a subclassification of adenocarcinomas of the oesophago-gastric junction. The possibility of a relationship between antigen expression and the presence or absence of Barrett's metaplastic epithelium was also studied. Methods and results: CK7, CK20, MUC1, MUC2 and MUC5AC were visualized in six adenocarcinomas of the distal oesophagus, 29 adenocarcinomas of the oesophago-gastric junction and eight adenocarcinomas of the proximal stomach. CK7, CK20 and MUC1 were strongly expressed in the great majority of all neoplasms under study, whereas MUC2 and MUC5AC were absent or only faintly detectable. CK20 exhibited a significantly stronger expression in poorly differentiated tumours (G3) and MUC1 immunoreactivity correlated with tubular and papillary versus signet-ring cell histopathology. Other statistically significant correlations between antigens and histopathological features (pTNM stage, grading, histopathological subtype, presence/absence of Barrett's epithelium) were not observed. Conclusions: According to our results, most adenocarcinomas of the oesophago-gastric junction show a CK7+, CK20+, MUC1+ phenotype irrespective of the presence or absence of Barrett's epithelium. The immunohistochemical data suggest a similar histogenesis of these tumours.