How should we grade CIN?

How should we grade CIN? The grading of cervical intraepithelial neoplasia (CIN) is problematic. CIN represents a morphological continuum, but biopsies displaying this lesion are classified into two (e.g. Bethesda) or three grade categories, sometimes with poor reproducibility. There are also difficulties in reliably distinguishing low‐grade CIN from its reactive simulants. Because of problems with inter‐ and intra‐observer disagreement in the grading of CIN and the diagnosis of low‐grade lesions, three expert contributions were commissioned to address the question `how should we grade CIN?'.