Cytologic features of high-grade squamous intraepithelial lesion in ThinPrep Papanicolaou test slides: comparison of cases that performed poorly with those that performed well in the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology

Performance of specific morphologic features in distinguishing low-grade squamous intraepithelial lesions from high-grade squamous intraepithelial lesions in borderline cases: a College of American Pathologists Cytopathology Committee multiobserver study

INTRODUCTION

Distinguishing between low-grade squamous intraepithelial lesions (LSIL) and high-grade squamous intraepithelial lesions (HSIL) can be difficult on certain Papanicolaou (Pap) tests, hindering interobserver concordance. We investigated the variables influencing the interpretation of LSIL versus HSIL in Pap test slides rejected from the College of American Pathologists PAP education program.

MATERIALS AND METHODS

Eleven cytologists, who were unaware of the reference interpretation, examined 21 Pap slides (11 submitted as LSIL and 10 as HSIL) rejected from the PAP education program and recorded the number of LSIL cells, HSIL cells, keratinized dysplastic cells, LSIL clusters with mixed HSIL cells, atypical squamous metaplasia, atypical glandular cells, the presence of inflammation or infectious organisms, and the overall interpretation (LSIL or HSIL). We evaluated the significance of these 11 variables using a nonlinear mixed model analysis.

RESULTS

LSIL had greater concordance (92 of 121 responses; 76.0% concordance) than HSIL (68 of 110 responses; 61.8% concordance; P < 0.001). The only predictors of misclassified cases were the number of atypical squamous metaplastic cells and the number of HSIL cells (P < 0.001). The more of these cells identified, the more likely the reviewers were to classify the slide as HSIL. The reproducibility of the diagnosis was fair (Gwet's agreement coefficient, 0.33).

CONCLUSIONS

Interobserver reproducibility is a challenge for a subset of cases with features intermediate between LSIL and HSIL. Atypical squamous metaplasia and dysplastic nuclei with a nuclear/cytoplasmic ratio greater than one half of the cell volume (HSIL) present on a Pap test influenced the likelihood that a reviewer would interpret the case as HSIL rather than LSIL.

Low-Grade Squamous Intraepithelial Lesion or High-Grade Squamous Intraepithelial Lesion? Concordance Between the Interpretation of Low-Grade Squamous Intraepithelial Lesion and High-Grade Squamous Intraepithelial Lesion in Papanicolaou Tests: Results From the College of American Pathologists PAP Education Program

Context.—

Obtaining diagnostic concordance for squamous intraepithelial lesions in cytology can be challenging.

Objective.—

To determine diagnostic concordance for biopsy-proven low-grade squamous intraepithelial lesion (LSIL) and high-grade squamous intraepithelial lesion (HSIL) Papanicolaou test slides in the College of American Pathologists PAP Education program.

Design.—

We analyzed 121 059 responses from 4251 LSIL and HSIL slides for the interval 2004 to 2013 using a nonlinear mixed-model fit for reference diagnosis, preparation type, and participant type. We evaluated interactions between the reference diagnosis and the other 2 factors in addition to a repeated-measures component to adjust for slide-specific performance.

Results.—

There was a statistically significant difference between misclassification of LSIL (2.4%; 1384 of 57 664) and HSIL (4.4%; 2762 of 63 395). There was no performance difference between pathologists and cytotechnologists for LSIL, but cytotechnologists had a significantly higher HSIL misclassification rate than pathologists (5.5%; 1437 of 27 534 versus 4.0%; 1032 of 25 630; P = .01), and both were more likely to misrepresent HSIL as LSIL (P &lt; .001) than the reverse. ThinPrep LSIL slides were more likely to be misclassified as HSIL (2.4%; 920 of 38 582) than SurePath LSIL slides (1.5%; 198 of 13 196), but conventional slides were the most likely to be misclassified in both categories (4.5%; 266 of 5886 for LSIL, and 6.5%; 573 of 8825 for HSIL).

Conclusions.—

More participants undercalled HSIL as LSIL (false-negative) than overcalled LSIL as HSIL (false-positive) in the PAP Education program, with conventional slides more likely to be misclassified than ThinPrep or SurePath slides. Pathologists and cytotechnologists classify LSIL equally well, but cytotechnologists are significantly more likely to undercall HSIL as LSIL than are pathologists.

Automatic failure in gynecologic cytology proficiency testing. Results from the College of American Pathologists proficiency testing program

CONTEXT

Automatic failure in gynecologic cytology proficiency testing occurs when a high-grade lesion or carcinoma (HSIL+, Category D) is misinterpreted as negative for intraepithelial lesion or malignancy (Category B).

OBJECTIVES

To document the automatic failure rate in 2006 and 2007 from the College of American Pathologists proficiency testing program (PAP PT) and compare them to projected values from 2004.

DESIGN

Identify automatic failures from PAP PT in 2006 and 2007 and compare the rates of failure regarding participant and preparation type to validated slides in the College of American Pathologists Interlaboratory Comparison Program in 2004.

RESULTS

There were 65 264 participant responses for HSIL+ slides included in this analysis from 2006 and 2007. Overall, 1% (666 of 65 264) of the HSIL+ responses were classified as negative, resulting in automatic failure for the participant. There were significantly fewer automatic failures in 2007 as compared with either 2006 or projected from 2004 data (P < .001). Conventional preparations had a lower automatic failure rate than liquid-based preparations but only for 2006. Both pathologists and cytotechnologists interpreting liquid-based preparations faired better than projected from 2004 data.

CONCLUSIONS

The automatic failure rate in PAP PT is lower than expected based on 2004 data from the College of American Pathologists Interlaboratory Comparison Program. Automatic failures are a relatively small component (1% or less) of proficiency testing failures. The rate of automatic failure decreased from 2006 to 2007 and may be due to loss of poor performers in the testing pool, the test-taking environment, or removal of less robust slides from the program.

Decrease in numbers of glandular cell groups in post-LLETZ liquid-based cytology preparations

OBJECTIVE

Large loop excision of the transformation zone (LLETZ) has become standard of care in the management of cervical squamous neoplasia and with cone biopsy glandular intraepithelial neoplasia. Controversy remains about the long-term effects of this traumatic procedure. The aim of this study was to count and compare the number of endocervical glandular cell groups in pre- and post-LLETZ cervical preparations using liquid-based cytology to establish a cyto-morphological correlate of destruction of the transformation zone.

METHODS

The cytology/histology correlation audit records of the Cytopathology Department of St Luke's Hospital in 2003 and early 2004 were used to select patients with a cytological diagnosis of high grade dyskaryosis followed by LLETZ. Only those cases with post-LLETZ cytological follow-up were selected. Cases using conventional smears were excluded. One hundred and twenty slides (60 pairs of slides) in total were retrieved. The cases underwent review and all groups of >3 glandular cells in each slide were counted by AM while blinded as to whether smears were pre- or post-LLETZ. Medians were compared using a Mann-Whitney U-test.

RESULTS

The median number of groups of endocervical glandular cells of the pre-treatment group was 5.5 and of the post-treatment group was 2.0. There were significantly fewer endocervical glandular cell groups in the post-LLETZ population (P = 0.03).

CONCLUSIONS

The number of endocervical glandular groups in cervical cytological preparations decreases significantly following LLETZ procedure. This suggests that cytological follow-up may not be as useful in glandular neoplasia cases. Few or absent glandular cell groups in post-LLETZ preparations may have implications for adequacy assessment.

Evaluation and significance of hyperchromatic crowded groups (HCG) in liquid-based paps

OBJECTIVE

Hyperchromatic crowded groups (HCG), a term first introduced into the cytology literature by DeMay in 1995, are commonly observed in Pap tests and may rarely be associated with serious but difficult to interpret lesions. In this study, we specifically defined HCG as dark crowded cell groups with more than 15 cells which can be identified at 10x screening magnification.

METHODS

We evaluated consecutive liquid-based (Surepath) Pap tests from 601 women (age 17-74 years, mean age 29.4 yrs) and observed HCG in 477 cases. In all 477 HCG cases, Pap tests were found to be satisfactory and to contain an endocervical sample. HCG were easily detectable at 10x screening magnification (size up to 400 um, mean 239.5 um) and ranged from 1 to 50 (mean 19.5) per Pap slide.

RESULTS

HCG predominantly represented 3-Dimensional groups of endocervical cells with some nuclear overlap (379/477--79%), reactive endocervical cells with relatively prominent nucleoli and some nuclear crowding (29/477--6%), clusters of inflammatory cells (25/477--5.2%), parabasal cells (22/477--4.6%), endometrial cells (1/477--0.2%). Epithelial cell abnormalities (ECA) were present in only 21 of 477 cases (4.6%). 18 of 21 women with HCG-associated ECA were less than 40 years old; only 3 were = or > 40 years. HCG-associated final abnormal Pap test interpretations were as follows: ASCUS (6/21--28%), LSIL (12/21--57%), ASC-H (2/21--9.5%), and HSIL/CIN2-3 (3/21--14%). The association of HCG with ECA was statistically significant (p = 0.0174. chi-square test). In patients with ECA, biopsy results were available in 10 cases, and 4 cases of biopsy-proven CIN2/3 were detected. Among these four cases, HCG in the Pap tests, in retrospect represented the lesional high grade cells in three cases (one HSIL case and two ASC-H cases). Interestingly, none of the 124 cases without HCG were found to have an epithelial cell abnormality.

CONCLUSION

We conclude: a. HCG are observed in a high proportion of cervical smears. b. In the vast majority of cases, HCG are benign. c. ECA were only observed in cases with HCG. This observation is consistent with the hypothesis that the presence of HCG in Pap tests most often represents adequate sampling of the transformation zone, thus increasing the chances of detecting an epithelial cell abnormality. d. Only a few cases with HCG were associated with a serious ECA, but careful scrutiny of all HCG appears warranted to avoid the potential diagnostic pitfall of a significant false negative interpretation.

The potential for failure in gynecologic regulatory proficiency testing with current slide validation criteria: results from the College of American Pathologists Interlaboratory Comparison in Gynecologic Cytology Program

CONTEXT

Current regulatory proficiency testing scoring results in an automatic failure for identifying high-grade squamous intraepithelial lesion (HSIL) as negative.

OBJECTIVE

The College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology data from January 2004 to April 2005 were analyzed to estimate the percentage of failure based on negative responses for HSIL and validation criteria.

DESIGN

More than 15,000 participants received field-validated and educational slide sets for conventional, ThinPrep, and SurePath modules. Educational sets fulfilled the validation criteria of the Center for Medicare and Medicaid Services, which required the consensus diagnosis of biopsy-proven HSIL (not field-validated) after review by 3 pathologists. The College of American Pathologists field validation required at least 20 responses to the HSIL+ series, with 70% matched to HSIL+ (standard error < or = 0.05). Minimum regulatory proficiency testing failure estimates were based on incorrect negative responses for the reference category of HSIL.

RESULTS

For both cytotechnologists and pathologists, there was a statistically significant higher failure rate for slides that were not field-validated versus those that were field-validated. In conventional modules, 5.3% of the slides that were not field-validated were called negative, versus 1.2% of the field-validated slides. In all liquid-based preparations, 4.0% of the non-field-validated versus 2.2% field-validated slides were called negative. Pathologists would have failed more often than cytotechnologists for the slides that were not field-validated, whereas there was no statistical difference in failure performance with field-validated slides.

CONCLUSIONS

Failures were significantly greater with the slides that were not field-validated for both conventional and liquid-based preparations (ThinPrep only) and have implications for both regulatory proficiency testing and expert legal review. Poor performance of pathologists relative to that of cytotechnologists may reflect a lack of prescreening of slides or scope of practice issues.

Robustness of validation criteria in the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology

CONTEXT

Field validation of slides used in gynecologic cytology proficiency testing has surfaced as an important issue. Although the precision of diagnoses in peer-reviewed educational programs has been examined, the robustness of the validation criteria for specific types of interpretations used in proficiency testing has not been previously studied.

OBJECTIVE

To evaluate the robustness of validation criteria for slides entering an educational slide program.

DESIGN

We reviewed the results of the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology and compared the robustness of validation criteria for different reference diagnoses, using a total of 16,948 circulating slides.

RESULTS

Validation criteria could be divided into 2 significantly different groups. The criteria for herpes, Trichomonas, squamous cell carcinoma, and adenocarcinoma were significantly more robust than the diagnoses of unsatisfactory; negative for intraepithelial lesion and malignancy, not otherwise specified; low-grade squamous intraepithelial lesion; and high-grade squamous intraepithelial lesion (P < .001).

CONCLUSIONS

The validation criteria used in the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology show 2 different levels of robustness or redundancy. These results have implications for the design of fair proficiency tests. Proficiency testing can be designed with the necessary number of reviews needed for slide validation.

Testing automated liquid-based cytology samples with a manual liquid-based cytology method using residual cell suspensions from 500 ThinPrep cases

We report a technical improvement upon a previously disclosed manual liquid-based cytology (MLBC) method; and, we use the improved method to prepare slides from residual ThinPrep specimens in order to see how often ThinPrep diagnoses correspond to diagnoses derived from exhaustive examination of their parent sample suspensions. Residual cell suspensions from 500 ThinPrep cases comprising (1) 20 low-grade squamous intraepithelial lesions (LSILs); (2) 200 high risk (HR) negatives and 20 ASC-US; and (3) 260 screening cytology specimens were studied. Institutional review committee guidelines allowed us to know diagnoses by groups of specimens, but did not allow us to know individual patient diagnoses, so we could not perform case-by-case matched outcome-comparisons. Cells were concentrated by conventional centrifugation and sedimented into a polymer gel that was then vortex-mixed and converted into a viscous cell-rich suspension. The cell suspension was smeared between two clean glass slides, which were air-dried and stained with the Papanicolaou stain. Two study-sets were created, comprising one slide from each case. Each of the two study sets was examined by two cytopathologists, and discordant diagnoses were adjudicated. Because of the ambiguity involved in the "atypical" (ASC-US, ASC-H, AGC) diagnosis categories, only outcomes at the level of LSIL or greater were recorded. All MLBC SILs were digitally imaged and abnormal slides plus digital images were sent to the laboratory that provided the residual automated liquid-based cytology (ALBC) suspensions. The final diagnoses were confirmed by the laboratory that provided the residual ALBC specimens. MLBC slides of the 20 LSIL cases afforded 2 high-grade squamous intraepithelial lesions (HSILs) and 18 LSILs. Those of the 200 HR-Negatives showed 3 HSILs and 30 LSILs; and those of the 20 HR-ASC-US showed 3 HSILs and 9 LSILs. MLBC slides of the 260 screening cytology specimens showed 1 Carcinoma, 3 HSILs and 20 LSILs; affording 3 HSILs and 14 LSILs more than originally diagnosed. The MLBC method of this report is useful for preparing cell suspensions for cytological examination. Our analytical method was exhaustive and used nearly all of the cell material that was provided to us for analysis; therefore, we conclude that this approach is useful for determining how well ALBC instruments represent their parent sample suspensions. It appears that "rare events" may be overlooked when limited sample aliquots are analyzed by ALBC instruments, and this probably accounts for our increased discovery of SILs by the MLBC method. Also, SILs often present as aggregates of cohesive cells which, if overlooked or ineffectively transferred to ALBC slides, would not be diagnosed.

Comparing methods to measure error in gynecologic cytology and surgical pathology

CONTEXT

Both gynecologic cytology and surgical pathology use similar methods to measure diagnostic error, but differences exist between how these methods have been applied in the 2 fields.

OBJECTIVE

To compare the application of methods of error detection in gynecologic cytology and surgical pathology.

DATA SOURCES

Review of the literature.

CONCLUSIONS

There are several different approaches to measuring error, all of which have limitations. Measuring error using reproducibility as the gold standard is a common method to determine error. While error rates in gynecologic cytology are well characterized and methods for objectively assessing error in the legal setting have been developed, meaningful methods to measure error rates in clinical practice are not commonly used and little is known about the error rates in this setting. In contrast, in surgical pathology the error rates are not as well characterized and methods for assessing error in the legal setting are not as well defined, but methods to measure error in actual clinical practice have been characterized and preliminary data from these methods are now available concerning the error rates in this setting.

Hyperchromatic Crowded Groups in Cervical Cytology—Differing Appearances and Interpretations in Conventional and ThinPrep Preparations: A Study From the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology

Context.—The practice of gynecologic cytology requires that high-grade squamous intraepithelial lesion (HSIL) be precisely recognized. In this regard, hyperchromatic crowded groups are known to be difficult to classify in conventional gynecologic cytology, but whether this is true in ThinPrep specimens is uncertain.

Objective.—To assess whether hyperchromatic crowded groups of cells in challenging HSIL cases are a problem in ThinPrep preparations, and whether these groups differ in appearance from those of conventional smears.

Design.—Sixteen images were taken from both conventional smears and ThinPrep slides that had a reference diagnosis of HSIL in the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology, but had performed poorly on subsequent participants' reviews. These 32 representative images were of hyperchromatic crowded groups and were classified by 20 Cytopathology Resource Committee members (17 pathologists and 3 cytotechnologists), who were masked to the reference diagnosis. A consensus classification was derived using the majority opinion of the individual reviewers. Finally, 5 cytologic features were assessed for those images that were interpreted as abnormal by the consensus classification.

Results.—None of the 32 images was uniformly interpreted as either benign, squamous lesion, or glandular lesion on individual review. Only 27% of individual interpretations of conventional smear images and 15% of ThinPrep images were interpreted as HSIL/squamous cell carcinoma (P &lt; .001). Individual interpretations of ThinPrep images as glandular lesions (60%) were more often made than those of conventional smears (44%, P &lt; .001). The consensus interpretation of ThinPrep images was glandular lesion in 75% of cases, whereas fewer than 50% of the consensus interpretations of conventional smear images were in this category. Conventional smear images were characterized by elongate nuclei (43%) and large nuclei (71%), whereas ThinPrep images more often showed rounded smooth edges (53%) and small nuclei (80%), and were recognized as a glandular lesion.

Conclusions.—Hyperchromatic crowded groups of cells are a source of difficulty in challenging HSIL cases for both conventional smears and ThinPrep specimens. In conventional smears, these groups are more likely to be labeled as a squamous lesion, owing to their elongate and large nuclei. In ThinPrep specimens, however, these groups are more likely to be labeled as glandular lesions, owing to their smooth contoured borders and small nuclei.

Results of multiple-slide, blinded review of Papanicolaou slides in the context of litigation. Determining what can be detected regularly and reliably

BACKGROUND

Multiple-slide, blinded review has been endorsed by several cytology and pathology organizations as the most appropriate method for the review of cervicovaginal specimens in the context of litigation. This process involves review of litigation slides in a blinded manner by multiple independent cytotechnologists and the comparison of those results with those of validation cases that are comprised of known abnormalities with biopsy follow-up. To the authors' knowledge, the results of this method have not been previously published.

METHODS

The results of the blinded review program at the Center for Cytopathology and Molecular Research at the Medical University of South Carolina for the years 1998-2004 were reviewed.

RESULTS

A total of 135 litigation slides and 122 validation slides were reviewed. The interpretations of these cases were found to be significantly different (P < 0.001). Litigation cases were significantly more likely to be interpreted as either negative for intraepithelial lesion (NIL) or atypical squamous cells/atypical glandular cells (ASC/AGC) (P < 0.001). The results appeared to be independent of the individual cytotechnologists involved. Approximately 10% of litigation cases were called at least ASC/AGC by all observers and 4% were interpreted as NIL by all observers. For litigation cases, ASC/AGC was found to be just as reproducible as high-grade squamous intraepithelial lesion. The results demonstrated that only 10% of litigation cases are regularly and reliably identified as abnormal, whereas a single review as performed by an expert cytologist can be expected to classify 56% of cases as abnormal.

CONCLUSIONS

This program suggests that a majority of litigation cases are not regularly and reliably identified as abnormal, and a single review will routinely overestimate the percentage of cases that are identified regularly and reliably.

Cytologic features of adenocarcinoma, not otherwise specified, in conventional smears: comparison of cases that performed poorly with those that performed well in the College of American Pathologists Interlaboratory Comparison Program in cervicovaginal cytology

CONTEXT

Characteristic cytologic features have been identified that distinguish cases that are consistently identified from those that are sometimes missed in the College of American Pathologists Gynecologic Cytology Program for a variety of different lesions and preparations.

OBJECTIVES

To compare the cytologic features of cases of adenocarcinoma, not otherwise specified (NOS), in conventional smears that perform poorly and well.

DESIGN

The cytologic features of 21 conventional smear cases of adenocarcinoma, NOS, that performed poorly in the College of American Pathologists Interlaboratory Comparison Program were compared with 17 cases that performed extremely well.

RESULTS

Cases that performed well were significantly more likely to have greater than 1000 abnormal cells (P = .006), greater than 100 large abnormal cells (P = .006), large nuclei (P < .001), marked nuclear atypia (P = .02), and hyperchromasia (P = .02). Repair-like features were rare in both groups and were not significant (P = .71).

CONCLUSION

Conventional smears with a diagnosis of adenocarcinoma that were consistently identified were significantly more likely to have more abnormal cells, larger abnormal cells, larger nuclei, marked atypia, and hyperchromasia than cases that performed poorly.

Cytologic features of squamous cell carcinoma in conventional smears: comparison of cases that performed poorly with those that performed well in the College of American Pathologists Interlaboratory Comparison Program in cervicovaginal cytology

CONTEXT

Characteristic cytologic features have been identified that distinguish cases that are always identified from those that are sometimes missed in the College of American Pathologists Gynecologic Cytology Program for a variety of different lesions and preparations.

OBJECTIVE

To compare the cytologic features of cases of squamous cell carcinoma in conventional smears that perform poorly and well.

DESIGN

The cytologic features of 8 conventional smear cases of squamous cell carcinoma that performed poorly in the College of American Pathologists Interlaboratory Comparison Program were compared with 17 cases that performed extremely well.

RESULTS

A total of 2387 individual interpretations were recorded. Of the 86 incorrect responses, 6.2% were for repair, and 0.8% were for Trichomonas. Cases that performed well were significantly more likely to have greater than 1000 dysplastic cells (16/17 vs 4/8, P = .02) and be keratinized (13/17 vs 1/8, P = .007). Obscuring inflammation and cell size were not significant.

CONCLUSION

Conventional smears with a diagnosis of squamous cell carcinoma that were always identified were significantly more likely to have greater than 1000 cells and be keratinized than cases that performed poorly.

Cytologic features of high-grade squamous intraepithelial lesion in conventional slides: what is the difference between cases that perform well and those that perform poorly?

CONTEXT

Previous studies have suggested that cases of high-grade squamous intraepithelial lesion in conventional smears and in ThinPrep specimens that are frequently misinterpreted as normal have relatively few small and hypochromatic dysplastic cells.

OBJECTIVE

To determine the cytologic differences between conventional Papanicolaou slides of high-grade squamous intraepithelial lesion that perform poorly and those that perform well.

DESIGN

We compared the cytologic features of 22 cases of conventional smears with high-grade squamous intraepithelial lesion that performed poorly in the College of American Pathologists Interlaboratory Comparison Program in Gynecologic Cytology with 45 cases of conventional smears that performed extremely well.

RESULTS

Cases that performed poorly were significantly more likely to have 50 or fewer single dysplastic cells (P = .003) and to have only small dysplastic cells (P = .01). Cases that performed well were also more likely to have more than 500 dysplastic cells (P = .002), to exhibit the presence of large dysplastic cells (P < .001), and to be keratinized (P = .03). Hypochromasia and the number of groups of dysplastic cells were not correlated with performance.

CONCLUSIONS

Conventional smears with high-grade squamous intraepithelial lesion with 50 or fewer single dysplastic cells, no large dysplastic cells, and lacking keratinization are highly associated with poor performance in this program.

Cytologic features of low-grade squamous intraepithelial lesion in thinprep papanicolaou test slides and conventional smears: comparison of cases that performed poorly with those that performed well in the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology

CONTEXT

Both conventional and ThinPrep Papanicolaou smears with high-grade squamous intraepithelial lesions that are frequently missed are known to have relatively few abnormal cells. Whether this is also true of cases of low-grade squamous intraepithelial lesion is not known.

OBJECTIVE

To compare the cytologic features of cases of low-grade squamous intraepithelial lesion that perform poorly with the features of cases that perform well.

DESIGN

The cytologic features of 10 ThinPrep Pap Test and conventional smear cases of low-grade squamous intraepithelial lesion that performed poorly in the College of American Pathologists Interlaboratory Comparison Program were compared with 46 ThinPrep Pap Test and conventional smear cases that performed extremely well. The numbers of abnormal cells were categorized into less than 50, 51 to 100, 101 to 250, 251 to 500, and more than 500.

RESULTS

The median number of abnormal cells for cases that performed poorly was less than 50, whereas the median number of abnormal cells for cases that performed well was between 101 and 250. Overall, cases that performed poorly were significantly more likely to have less than 50, less than 100, and less than 250 abnormal cells than cases that performed well (P < .001, P < .001, and P = .009, respectively). A minority of cases performed well even with very few abnormal cells and groups. The same findings were present when conventional smears and ThinPrep specimens were analyzed separately.

CONCLUSIONS

ThinPrep Pap Test cases and conventional smears with a diagnosis of low-grade squamous intraepithelial lesion that perform poorly in this program have significantly fewer abnormal cells than those that perform well. The median number of abnormal cells in cases that performed well is lower than that of comparable high-grade cases in the program.

The number of dyskaryotic cells on an initial ThinPrep cervical sample showing mild dyskaryosis has predictive value

OBJECTIVES

Recent National Health Service Cervical Screening Programme (NHSCSP) guidelines suggest referral for colposcopy following an initial result of mild dyskaryosis. The aim of this study was to investigate if the number of dyskaryotic cells counted on an initial ThinPrep cervical sample showing mild dyskaryosis has predictive value.

METHODS

Cases of mild dyskaryosis on ThinPrep cervical samples from 2002 were retrieved from the cytology department records of St Luke's Hospital. A total of 123 sequential cases with a first-time result of mild dyskaryosis on ThinPrep slides with follow-up cytology available in the same institution were identified. While blinded to outcome, the number of dyskaryotic cells was counted in each case. Follow-up colposcopy/histology information was retrieved where indicated. The number of dyskaryotic cells counted on each slide was collated with outcome data.

RESULTS

Of the 123 cases, six women were lost to follow-up. Seventy-three had a negative outcome, 27 had a low-grade outcome and 17 had a high-grade outcome. Only one of 17 high-grade outcome cases had < or = 15 dyskaryotic cells on the initial slide. The distribution of women with a negative/low-grade outcome and those with a high-grade outcome with >15 and < or = 15 dyskaryotic cells on the initial slide was tested using a chi-square test (P = 0.008). The negative predictive value for a high-grade outcome when < or = 15 dyskaryotic cells were present on the initial slide was 97.7%.

CONCLUSION

The number of dyskaryotic cells on ThinPrep slides showing mild cervical dyskaryosis has predictive value. The number of dyskaryotic cells may be used to select women suitable for cytological rather than colposcopic follow-up.