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

Is this the end of the line for the moderate dyskaryotic smear?

OBJECTIVE

The British Society for Clinical Cytology has recently proposed that the terminology for cervical smear reporting is to be changed from a 3-tier system (mild, moderate, severe dyskaryosis) to a 2-tier system of low-grade and high-grade dyskaryosis. This modification eliminates the central category of moderate dyskaryosis which would be incorporated into the high-grade group. The aim of this study was to investigate the role of the moderate dyskaryotic smear in clinical practice.

MATERIALS AND METHODS

A retrospective review of all women who were referred for colposcopy because of a moderate dyskaryotic smear was carried out for a 6-month period. Data collected included colposcopic impression, procedure performed and final histopathology. Two cytologists who were unaware of the original smear report were asked to reclassify these smears using the new 2-tier system. Their findings were compared with the documented colposcopic and histopathology results.

RESULTS

One hundred women with moderate dyskaryotic smears were referred for colposcopy during the study period. Most of these were reclassified as high-grade dyskaryosis using the new system. Fifty-six (72%) of the moderate dyskaryotic smears which were correctly regraded as high grade by cytologist 1 were found to have cervical intraepithelial neoplasia 2/3 on final histopathology, whereas for cytologist 2, 66 (68%) were found to have high-grade cervical intraepithelial neoplasia.

CONCLUSION

There is no clinical benefit in retaining the term moderate dyskaryosis. This study emphasizes the need for a uniform 2-tier system.

European guidelines for quality assurance in cervical cancer screening: recommendations for cervical cytology terminology

There are many different systems of cytology classification used in the member states of the European Union (EU) and many different languages. The following short annexe to Chapter 3 of the European Guidelines for Quality Assurance in Cervical Cancer Screening provides a framework that will allow different terminologies and languages to be translated into standard terminology based on the Bethesda system (TBS) for cytology while retaining the cervical intraepithelial neoplasia (CIN) classification for histology. This approach has followed extensive consultation with representatives of many countries and professional groups as well as a discussion forum published in Cytopathology (2005;16:113). This article will describe the reporting of specimen adequacy, which is dealt with in more detail elsewhere in Chapter 3 of the guidelines, the optional general categorization recommended in TBS, the interpretation/cytology result and other comments that may be made on reports such as concurrent human papillomavirus testing and the use of automation review and recommendations for management. The main categories in TBS will be described in the context of CIN, dyskaryosis and dysplasia terminologies so that all may be translated into the same framework. These guidelines should allow European countries to adapt their terminology in such a way as to make their screening programmes comparable with each other as well as with programmes elsewhere in the world.

Human papillomavirus testing with conventional Pap smear screening in three inner London community clinics

BACKGROUND AND METHODOLOGY

This observational study aimed to establish prevalence of high-risk human papillomaviruses (hrHPV) in women attending three inner London community clinics for routine screening and to pilot hrHPV testing in the triage of either borderline or negative cytology after previous abnormalities. Hybrid Capture 2 was carried out on brush samples taken alongside conventional smears from 1434 women aged 20-49 years. hrHPV positivity prompted earlier referral of women with previous abnormalities and either low-grade or negative cytology. Outcome at colposcopy was compared with the records of 1871 women aged 20-49 years attending colposcopy during the same period of time (routine colposcopies).

RESULTS

hrHPV was detected in 111/161 (68.9%) women with abnormal cytology, 76/460 (16.5%) with negative cytology after previous abnormalities and 105/813 (12.9%) with negative cytology and no previous abnormalities. Overall, hrHPV was detected in 292/1434 (20.4%) women in the study (95% CI 18.3-22.5). hrHPV prevalence increased with severity of cytological abnormality (p<0.001) and decreased with age both with negative and low-grade cytology (p<0.001). High-grade cervical intraepithelial neoplasia (CIN) biopsies were found more frequently in women in the study groups with low-grade (p<0.001) or negative cytology than in routine colposcopies, but more women in the study groups attended colposcopy (8.2% compared with 4.1% routine colposcopies, p<0.001).

CONCLUSIONS

hrHPV positivity increased detection of high-grade CIN in the study groups at the expense of more colposcopies. hrHPV negativity could reduce the need for investigation of low-grade cytology in women aged over 35 years and for surveillance after previous abnormalities.

Proposed Sheffield quantitative criteria in cervical cytology to assist the diagnosis and grading of squamous intra-epithelial lesions, as some Bethesda system definitions require amendment

OBJECTIVE

This study assesses the accuracy of published quantitative and qualitative criteria in the Bethesda System (TBS) for squamous intra-epithelial lesions.

METHODS

Quantitative image analysis was undertaken on illustrations from TBS publications and also from slides in Cytology Training Centre teaching sets. Comparisons were also made with the British Society for Clinical Cytology (BSCC) terminology in cervical cytology, using the illustrations in their terminology publication and amalgamating the results into their proposed new two-tier model.

RESULTS

TBS quantitatively defines low-grade squamous intra-epithelial lesions (LSIL) in both conventional and liquid-based cytology (LBC) preparations as showing nuclear enlargement more than x3 the area of a normal intermediate squamous cell nucleus. This study found that the increase in mean nuclear area was limited to only x2 in conventional preparations. In LBC (SurePath preparations, there was only a statistically non-significant x1.2 increase. This study identified a progressive and statistically significant reduction in mean cytoplasmic area from normal intermediate cells to LSIL and then to high-grade squamous intra-epithelial lesions (HSIL) in both conventional and LBC preparations. Furthermore, the most consistent quantitative finding in both conventional and LBC preparations was a statistically significant increase in the mean area and diameter ratios from normal intermediate cells to LSIL and then to HSIL. In all instances this varied from x2 to just below x3. This is in agreement with TBS, which states that the cytoplasmic area in HSIL is decreased leading to a marked increase in nuclear to cytoplasmic (NC) ratio. With the exception of an increase in mean nuclear area in conventional preparations from normal intermediate cells to LSIL, the predominant cause for this increase in NC ratios was a reduction in mean cytoplasmic area. The numerical increase in NC ratio for LSIL identified in this study was greater than implied by the 'slightly increased' statement in TBS. TBS comments that some HSIL cells can have the same degree of nuclear enlargement as in LSIL and that other HSIL cells may have much smaller nuclei than in LSIL. Both of these qualitative comments were supported in this study. The mean diameter NC ratios of 33% and 50% could provide useful diagnostic assistance in the distinction of normal intermediate cells and LSIL and between LSIL and HSIL, respectively. Because of overlapping individual ranges, however, additional diagnostic features such as nuclear morphology must be used in the distinction of normal intermediate cells, LSIL and HSIL. No statistical difference was identified in the mean diameter NC ratios between ASC-US and LSIL in TBS publications. In addition, the proposed new BSCC low and high grades of squamous abnormality were not statistically different from ASC-US/LSIL and HSIL, respectively. This provides support that the proposed BSCC two-tier system of squamous abnormalities is comparable to TBS. This study shows that LBC has variable but major and significant effects on nuclear and cytoplasmic morphology and that quantitative definitions in conventional preparations cannot be automatically extrapolated to LBC methodology.

CONCLUSIONS

The study shows that some TBS quantitative and qualitative criteria require amendment and that an alternative quantitative approach, such as diameter NC ratio has a more valid scientific evidence base. Furthermore, use of NC ratios avoids the problems associated with the variable changes in nuclear and cytoplasmic areas, occurring between conventional and different commercial LBC preparations. By contrast, classifications based on area comparisons must be tailored to the specific conventional or commercial LBC preparation.

Proposed Sheffield quantitative criteria in cervical cytology to assist the grading of squamous cell dyskaryosis, as the British Society for Clinical Cytology definitions require amendment

OBJECTIVE

In 1986, the British Society for Clinical Cytology (BSCC) published quantitative criteria to assist diagnosis in a three-tier grading system of squamous cell dyskaryosis. In dyskaryotic cells, area nuclear to cytoplasmic (NC) ratios below 50%, between 50% and 66% and over 66% were defined as equating with mild, moderate and severe grades respectively. Following the Terminology Conference in 2002, however, the BSCC recommended on their website that the three-tier model should be replaced by a new two-tier system of low- and high-grade squamous abnormalities. The latter broadly equate with the two-grade Bethesda System (TBS) for reporting squamous intraepithelial lesions. The purpose of this study was to assess the accuracy and reproducibility of the BSCC three-tier quantitative definitions, to investigate if they were applicable to liquid-based cytology (LBC) and to see how they related to the proposed new two-tier BSCC system.

METHODS

Quantitative image analysis was undertaken on illustrations from the 1986 BSCC terminology publication and on microscope slides from external quality assessment and Cytology Training Centre teaching sets.

RESULTS

Analysis of mean NC ratios showed that mild, moderate and severe dyskaryosis exist as statistically different populations. Overlap of NC ratio ranges, however, limits their practical application in the three-tier model, although interestingly no overlap was noted between mild and severe dyskaryosis. No grade of dyskaryosis had a mean area NC ratio over 50%, indicating that the BSCC quantitative definitions are incorrect. The mean diameter NC ratios for mild, moderate and severe dyskaryosis were found to be 40%, 49% and 66% respectively. Accordingly it is possible that those reporting cervical cytology could be interpreting the BSCC NC ratios as meaning diameter rather than area. Amalgamation of the three-tier results into the proposed two-tier model shows that the resulting mean NC area and diameter ratios identify statistically different low- and high-grade populations. The reduced degree of overlap, however, of NC ratio ranges in the two-tier model implies that NC ratios could have a useful practical role in the separation of the low- and high-grade categories. The two categories were reasonably well separated by mean area and diameter NC ratios of 25% and 50% respectively. A two-tier model combining mild with moderate rather than severe dyskaryosis was found to be a statistically valid alternative but gave rise to NC ratios that would be difficult to use in practice. Except for moderate dyskaryosis, no significant differences were identified between the mean NC ratios of either conventional and LBC preparations or LBC preparations using two different commercial methodologies (SurePath and ThinPrep). Differences, however, were noted in area measurements between SurePath and ThinPrep and this has potential implications for classifications (such as TBS) using area comparisons as their basis. In addition, it was found that the increased NC ratio, associated with higher grades of dyskaryosis is more a consequence of progressive cytoplasmic area reduction rather than nuclear area increase. The similar NC ratios of borderline nuclear changes associated with human papilloma virus and mild dyskaryosis support the BSCC proposal that these can be combined to constitute a low-grade category. This study shows that the BSCC area NC ratio criteria of grading squamous cell dyskaryosis require amendment. In addition, this study supports the new BSCC recommendation of low- and high-grade squamous cell categories.

CONCLUSIONS

The study proposes Sheffield quantitative criteria to assist the grading of squamous cell abnormalities. Quantitative diameter NC ratio measurements, however, must always be accompanied by detailed assessment of qualitative morphological features and in particular those relating to nuclear chromatin. This is equally relevant to both two- and three-tier models.

BSCC, Bethesda or other? Terminology in cervical cytology European panel discussion

The European panel agreed that reproducibility and translatability of terminology in cervical cytology were essential, arguing well for harmonization of reporting systems. The majority at this meeting use a modification of the Bethesda system (BS). Local modifications involved reporting subcategories within high grade and low grade lesions, which would not alter the overall translatability of their systems both with each other and BS. The majority agree that low grade lesions with and without koilocytosis should be managed similarly as should high grade lesions (moderate dysplasia/CIN2 or worse). Those systems linking moderate dysplasia with mild rather than severe dysplasia would need to define moderate dysplasia as such, if their results were to be translatable, which would be preferable to their using a different definition of low grade and high grade lesions. Translation between systems might anyway be facilitated by reporting moderate dysplasia as a subcategory within high grade, which was favoured by most of those present. Therefore, there is no need for exact agreement of terminology if broad principles are agreed. This useful discussion adds weight to the British Society for Clinical Cytology recommendation that the new classification should be adopted by the UK National Health Service Cervical Screening Programme. If the new classification is adopted, the UK would join the European consensus opinion on terminology.

Terms without borders: An international approach to terminology

This article describes the similarities between different terminological systems for reporting the spectrum of abnormalities that comprise pre-cancerous, malignant and equivocal cellular changes in epithelial cells of the uterine cervix. In particular, the new terminology proposed by the British Society for Clinical Cytology (BSCC) is closely aligned with the Bethesda system (TBS) as modified in 2001. Both make a clear distinction between high-grade and low-grade intraepithelial abnormalities and identify certain categories of atypical or borderline changes that are suspicious for high-grade abnormalities.