Reduced expression of cytokeratin 4 and 13 is a valuable marker for histologic grading of esophageal squamous intraepithelial neoplasia.

Histologic evaluation of low-grade or high-grade intraepithelial neoplasia (LG-IN or HG-IN) of the esophagus is important for estimating the risk of progression to invasive carcinoma. Discrimination between LG-IN and HG-IN, or neoplasia and non-neoplastic lesion (NNL), however, is occasionally difficult. This study was designed to evaluate whether cytokeratin expression can be used for discrimination of these lesions. Esophageal Iodine-unstained lesions (n=154), less than 10 mm, were classified into HG-IN, LG-IN, and NNL. These lesions together with 154 foci of normal esophageal epithelium (NEE) were examined by immunohistochemistry for cytokeratins (CK4 and CK13), p53 overexpression, and the MIB-1 labeling index. The ratios of CK4- and CK13-positive staining were scored from 1 to 3. The CK4- and CK13-positive staining ratios were decreased in NNL (73% and 78%), LG-IN (55% and 69%), and HG-IN (33% and 48%), compared to NEE (91% and 95%). The differences between LG-IN and HG-IN, neoplasia and NNL, and among these three lesions and NEE were statistically significant (p < 0.005). The cytokeratin scores correlated with the MIB-1 labeling index (both: p < 0.0001), but not with p53 overexpression. CK4 and CK13 immunohistochemistry could be an objective method for evaluating the risk for progression to invasive carcinoma.