Squamous differentiation in carcinoma in situ of the cervix uteri. A cyto-histological correlation of malignant intraepithelial lesions with invasive carcinoma.

Cervical biopsies from 97 women with malignant cells in cervical scrape smears have been studied. Forty-eight patients had invasive squamous carcinoma, and 49 had intraepithelial lesions. Of these, six had dedifferentiated carcinoma in situ, nine had the differentiated lesions generally known as ;severe dysplasia', and 29 had both; the severity of the dysplasia remained doubtful in five patients. The ;severe dysplasia' was compared with invasive carcinoma. A cellular analysis of the biopsies showed that the two categories have a number of features in common, chiefly the presence of atypical and normal mitoses, nucleoli, horn cells, and giant cells. The stratification of the epithelium in ;severe dysplasia' is invariably abnormal and the architecture closely resembles that of invasive carcinoma. The cells in the smears from ;severe dysplasia' are similar to those in invasive carcinoma. It is suggested on the basis of these observations that a ;severe dysplasia' should be interpreted as a differentiated carcinoma in situ.