12 They found that the proliferative activities in the two areas were similar and they speculated that the mechanism of intraepithelial spread was multicentric occurrence (concept of field MLN0128 carcinogenesis) rather than lateral cell proliferation. Our results also showed that lesions with m3 or deeper invasion contain a significantly narrower area of low-grade dysplasia component than do lesions of m2 cancer. These results suggest that a low-grade dysplasia component would transform to
carcinoma in situ and invasive carcinoma along with tumor progression. Although we cannot conclude from our results that low-grade dysplasia is a precancerous lesion, the possibility that some lesions categorized as low-grade dysplasia in the WHO criteria have malignant potential
has been confirmed. However, our results showed that the low-grade dysplasia PCI-32765 order component in early invasive carcinoma had a significantly higher grade of atypia in cytological abnormalities than did the small low-grade dysplasia control cases. Although both lesions are simply categorized as low-grade dysplasia regardless of degree of abnormalities in the current WHO classification, the possibility that these lesions originally have different biological characters should be considered. Further study using molecular technology is needed to clarify this. Our results also revealed the risk of early invasive SCC of the esophagus being histologically diagnosed as low-grade dysplasia by click here endoscopic biopsy and thus being followed up without treatment. As for the actual reliability of histological diagnosis for endoscopic biopsy specimens, we previously studied histological results of EMR for esophageal lesions diagnosed as high-grade intraepithelial squamous neoplasia by endoscopic biopsy.13 Examination
of totally resected specimens revealed that over 30% of such lesions are actually invasive carcinoma and we concluded that endoscopists and pathologists must accept the fact that discrepancies between diagnosis of a biopsy specimen and that of the final resection specimen cannot be avoided. However, performing EMR for all esophageal lesions diagnosed as low-grade dysplasia by endoscopic biopsy is not realistic. Most of the low-grade dysplasia components in early invasive carcinoma observed in our study showed degrees of cytological abnormalities similar to those in the tumor invasive front. We consider that another nomenclature for squamous cell lesions with a high degree of cytological abnormalities confined to the lower half of the epithelium is required. Only a half decade ago, most cases of intraepithelial squamous neoplasia of the esophagus were diagnosed on the basis of nuclear features and changes in the epithelial structure by Japanese pathologists.