[Reevaluation of precancerous lesion of squamous cell carcinoma]

One hundred fifty-nine cases of esophageal carcinoma were reviewed retrospectively. There were 75 dysplastic lesions in 32 cases (20.1%). Although the continuity of dysplastic lesions to the areas of carcinoma was not so frequent (48.0%), it was more often encountered in severe rather than in moderate or mild dysplasia, which suggested some relationship between the severity of dysplasia and carcinoma. Using a silver colloid staining technique, nucleolar organizer region-associated proteins (NOR) were studied in paraffin sections of 22 normal epithelia, 22 dysplasias, 17 carcinomas in situ (CIS), and 14 invasive carcinomas. The mean numbers of NOR in the nucleus were 1.77 +/- 0.14 (mean +/- SD) in normal epithelium, 2.16 +/- 0.30 in dysplasia, 2.78 +/- 0.51 in CIS, and 3.67 +/- 0.85 in invasive carcinoma. On the other hand, the NOR number in the atypical layer of the dysplasia was 2.60 +/- 0.39, which was almost the same level as that of CIS. These results suggest that atypical layers in esophageal dysplasia already have the same level of proliferative activity judging from the NOR numbers. Immunohistochemical staining for P53 protein revealed that, in the 13 cases with positive staining of the cancer tissue, 79.1% of dysplastic lesions were also positively stained. These results suggested that, although dysplasia was not carcinoma because of the restriction in the mucosa without invasion, the biological nature of dysplasia might be considered as serious a lesion as carcinoma itself.