Histology of cervical intraepithelial neoplasia and the role of biomarkers

Accurate histological grading of cervical intraepithelial neoplasia (CIN) lesions is important for clinical management of patients, because CIN1 and CIN2 and 3 lesions are treated differently. In general, there tends to be poor inter and intra-observer reproducibility of CIN grade evaluation among pathologists. In particular, the differential diagnosis between immature squamous metaplasia and CIN1 and 2, or between low-grade (CIN1) and high-grade (CIN2 and 3) lesions, tend to be difficult. These difficulties mean that patients tend to be over-treated for CIN lesions, which will naturally regress. Collectively, this highlights the need for alternative approaches and specific biomarkers to aid objective CIN lesion grading, and to identify true high-grade cervical disease. In this review we focus on the aetiology, pathobiology, the natural history of CIN, current issues with diagnosis and classification of CIN and the diagnostic and prognostic utility of specific biomarkers in identifying true cancerous precursor lesions.