[Histologic classification and terminology of precancerous lesions of the cervix].

INTRODUCTION Precancerous changes of the cervix frequently occur in women in their reproductive age and are associated with sexually transmitted diseases. The evolution of these lesions qualifies them as precursors of malignancy, and their origination is associate with various risk factors, human papillomavirus (HPV) being the most important one. A proper clinical approach to and treatment of these changes depend on histologic diagnosis, which must be both terminologically adequate and apprehensive. PREVIOUS CLASSIFICATIONS AND TERMINOLOGY The continuous change in nomenclature and lack of a uniform terminology has become the source of confusion and misunderstanding between gynecologists and pathologists. The term carcinoma in situ was first introduced in 1930 to denote the lesion, which is a reliable precursor of malignancy. Less intensive epithelial changes of the cervix were classified as dysplasia. Depending on extensive the change was, dysplasias were subclassified into mild, moderate and severe. Carcinoma in situ and various degrees of dysplasias were more precisely defined at the First International Congress of Exfoliative Cytology, which has also enabled the biological differentiation between these entities. The histologic differentiation of these lesions was, however, subjective and quite unreliable. UP-TO-DATE CLASSIFICATION AND TERMINOLOGY: Cellular changes in carcinoma in situ and in severe dysplasias were mutually so similar that pathologists could not make a reproducible difference between these lesions. Therefore, a conclusion was reached that these changes were one and the same process, whereas the differences were merely of quantitative nature. This discovery resulted in a terminological change, i.e. in a unique term--cervical intraepithelial neoplasia (CIN), with its gradation from 1 to 3. The 3rd grade of cervical intraepithelial neoplasia, according to the new terminology, encompassed changes which pathologists could not properly differentiate before. Many other changes with various, mostly descriptive terminology have also been included in the CIN category, thus preventing misunderstanding between pathologists and gynecologists. Besides the CIN classification, which has been most widely used today, there is also a division into only two biologically different categories: low-grade cervical intraepithelial neoplasia (Lo-CIN) and high-grade cervical intraepithelial neoplasia (Hi-CIN). The latter modification is included in the Bethesda system of cytologic diagnoses as low-grade squamous intraepithelia lesion (L-Sil) and high-grade squamous intraepithelial lesions (H-Sil). CONCLUSION The use of a uniform terminology and classification minimizes the problem of diagnosing precancerous cervical lesions and enables adequate clinical treatment of these patients.