BSCC terminology for cervical cytology: two or three tiers? Why not five, seven or even 14?

Any classification of cervical cytology should take account of the fact that it is dealing with a continuous spectrum of change in more than one cell type. It is tempting, and to some extent necessary, to simplify the classification but it is worth remembering that consistency is not necessarily improved by reducing the number of categories. The full spectrum of categories recognized in different systems is shown in Figure 1a, many of which may be used in free text reports with the proposed terminology. Cytopathologists recognize that with current technology they are unable to distinguish HPV infection from mild dyplasias/CIN1 and aim to avoid using any of those terms in cytology reports. Combining moderate with severe dysplasia/CIN as high-grade provides a pragmatic method of managing the majority of cases significantly at risk of progression to invasive cancer, but there is no precise line between mild and moderate dyskaryosis any more than there is between any other degree of abnormality. The BSCC have proposed to mirror TBS by merging the categories as shown in Figure lb, but there may be an argument for continuing the sub-classification within 'high-grade dyskaryosis'. Perhaps regrettably, cytologists complicate matters further by surrounding the entire classification system with various shades of grey. These borderline cases should be reduced to a minimum, but it is clinically important to identify categories in which the changes have a relatively high probability of representing a clinically significant abnormality.