**2. Precursor lesions of cervical carcinoma**

Precursor lesions of both squamous cell carcinoma and adenocarcinoma are well defined, according to our current understanding of cervical neoplasia. However, years of scientific observations and research preceded the recognition of these lesions. Observations concerning spatial and/or temporal relationship between invasive carcinomas and non-invasive, intrae‐ pithelial alterations of the uterine cervix had been repeatedly reported in the past, as early as the end of the 19th century [24-27]. These observations resulted in the recognition of precan‐ cerous alterations of cervical epithelium, for which different terms and definitions have been used in the following years.

The terms carcinoma in situ and dysplasia have been in use for several decades, in order to describe non-invasive, intraepithelial lesions showing cytologic abnormalities akin to those of invasive carcinoma. In the late 1960's the concept of one disease spectrum was introduced, based on observed similarities between groups of lesions, which were considered as different grades of the same disease process, termed cervical intraepithelial neoplasia / CIN [28,29]. This terminology became the most widely used for the next decades and is currently in use in many laboratories worldwide.

The recognition of the important role[s] of human papillomavirus in cervical carcinogenesis gradually led to different approaches, concerning the whole group of HPV-related lesions and their classification, based on more recent biologic and molecular data [11,13,30,31]. Among them the distinction between two basic biological entities was included: specifically, between a productive viral infection and an intraepithelial neoplastic process. Several questions remain to be answered; however, on a practical level, patient management remains an important basis that influences and often guides choices of terminology.

In the last decades a binary system of classification based on The Bethesda System [TBS] has been mainly in use by cytopathologists; however, several histopathology laboratories world‐ wide have also adopted similar terminology. A binary system is more consistent with the current knowledge concerning HPV-related disease and is considered to form a basis for improved communication between gynaecologists and pathologists [31]. Moreover, the intermediate group (IN2) has not been shown to comprise a reproducible diagnostic category among pathologists.
