Overview and classification of cervical intraepithelial neoplasia
The anatomical region of transition between the columnar epithelium of the endocervical canal and the squamous epithelium of ectocervix is of great biological cellular activity due to the transformation of epithelium to another (metaplasia). Various physical, chemical and biological agents acting on this unstable cell population can induce cell morphological changes and structural and architectural epithelium, resulting in what is now called NCI, the original concept of Richart (1967), which has displaced to other concepts such as histological dysplasia and carcinoma in situ. Today it is considered that maturation and cellular alterations that occur in the epithelium of the cervix are sufficiently similar to conclude that developmental stages are the same entity, which only differ by the degree of total thickness of the epithelium is affected.
The histologic features of the NCI are:
1. The changes affect only the surface epithelium, although they may affect the stuffing glands.
2. Loss of stratification and cell polarity.
3. Lack of differentiation and maturation.
4. Nucleus / cytoplasm ratio increased and different size and cell morphology.
5. Hyperchromasia and irregular chromatin distribution.
6. Increased number of mitosis and abnormal mitosis.
The NCI is classified into three grades:
NCI grade I (mild dysplasia synonymous). Alterations affecting the lower third of the total thickness of the epithelium.
NCI grade II (moderate dysplasia synonymous). The alterations affect between one and two thirds of the total thickness of the epithelium.
NCI grade III (severe dysplasia synonym: carcinoma in situ). The changes extend throughout the thickness of the epithelium.