Oral carcinoma in situ.

Oral carcinoma in situ (CIS) as a histopathologic entity was studied in seventy-seven patients to determine the clinical and histologic parameters of the disease. There were forty-nine male and twenty-eight female patients, with 45.1 per cent of the lesions being described clinically as white, 15.9 per cent as red, and 8.5 per cent as a combination of the two. The high-risk sites for CIS were floor of the mouth (23.2 per cent of all lesions), tongue (22.0 per cent), and lips (in males only, 19.5 per cent). Histologically, there was a considerable range of variation in surface keratinization, thickness of epithelium, and certain cytologic alterations. The most consistent of all cytologic changes was loss of orientation of cells. There is no information available concerning possible regression of oral CIS, as is known for CIS of uterine cervix. Furthermore, there is no information concerning the frequency of or the period of transition from oral CIS to invasive carcinoma or whether all oral carcinoma is preceded by CIS. Further studies on this disease are essential.