Cytologic features of squamous cell carcinoma in ThinPrep slides: evaluation of cases that performed poorly versus those that performed well in the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology

Challenging lesions in cervical cytology: The elusive HSIL

Cervical cytology has been an integral part of cervical cancer screening since the mid-20th century with the implementation of screening protocols utilising Pap testing. During that time, cervical cancer has gone from the leading cause of cancer deaths in women to not even appearing in the top 10 causes of US cancer deaths. However, despite its long and widespread use, cervical cytology remains a diagnostically challenging area in the practice of cytopathology. Of particular importance for diagnosticians is the accurate diagnosis of high-grade squamous intraepithelial lesions (HSILs), given the significant risk of progression to invasive cervical cancer and the importance to patient management. Therefore, this review is presented in order to highlight the diagnostic features of HSIL, its various appearances, and important benign and neoplastic differential considerations with an emphasis on morphological clues that can aid in distinguishing between these different processes.

The Pap smear in inflammation and repair

Cytology of the uterine cervix is one of the most widely utilized tests and is best known primarily for the cytologic changes seen in precancerous lesions and invasive cancer of the uterine cervix. The more common inflammatory conditions of cervicitis and vaginitis are close clinical differentials, especially when they give rise to excessive blood-stained vaginal discharge. These infective conditions also result in variation in the appearance of otherwise benign squamous and glandular cells in cervical cytology specimens. A variety of physiologic and pathologic conditions are responsible for the conversion of polymicrobial flora of the vagina to a monomicrobial one. The latter may overgrow the others and result in inflammation of the cervix and the vagina. Chronic irritation of the cervix due to intrauterine devices, chemical irritants, inflammation/infection, endocrine changes, and reparative changes can lead to worrisome parakeratosis, hyperkeratosis, and squamous metaplasia of non-keratinized squamous mucosa of the cervix and the vagina and may mimic HPV-related changes. Although some benign changes are specific for certain infections, for example, Trichomonas infestation, most of the reactive and hyperplastic cell morphology are important to recognize only due to the significant morphologic overlap with neoplastic changes in cytology specimens. Identification of different pathogens specifically may not be relevant from a clinical point of view, but is undoubtedly a cytologists’ privilege to inform the clinician! This chapter describes in detail the cytoplasmic and nuclear reactive changes that are found in specific and non-specific inflammatory conditions. In addition, diagnostic pitfalls are emphasized where necessary.

The Differential Diagnosis of Reparative Changes and Malignancy: Performance in the College of American Pathologists Pap Education and Proficiency Testing Programs

Context.—

Repair is a challenging diagnosis and a significant source of false-positive (FP) interpretations in cervical cytology. No large-scale study of performance of repair in the liquid-based era has been performed.

Objective.—

To evaluate the performance of repair in the College of American Pathologists Pap Education and Proficiency Testing (PT) programs.

Design.—

The FP rate for slides classified as repair was evaluated by preparation type, participant type (cytotechnologist, pathologist, or laboratory), and program. The specific misdiagnosis category and individual slide performance were also evaluated. The rate of misclassification of slides as repair by participants for other diagnostic categories in the Pap Education program was assessed.

Results.—

The overall FP rate was 1700 of 12 715 (13.4%). There was no significant difference by program or preparation type. Within the Education program there was no difference by participant type, but pathologists' FP rate in the PT program (47 of 514, 9.1%) was significantly better than cytotechnologists in the PT program (51 of 380, 13.4%) and pathologists in the Education program (690 of 4900, 14.1%). High-grade squamous intraepithelial lesions/cancers (HSIL+) accounted for 1380 of 1602 FP interpretations (86%) in Education, but 43 of 98 (43.9%) in PT. Most slides had a low rate of misclassification, but a small number were poor performers. False-negative diagnosis of HSIL+ as repair was less common, ranging from 0.7% to 1.8%.

Conclusions.—

Despite initial indications that liquid-based cytology might reduce the rate of misclassification of repair, FP interpretations remain common and are no different by preparation type. Misclassification is most commonly as HSIL or carcinoma, potentially resulting in significant patient harm.

Association of Bacterial Vaginosis and Human Papilloma Virus Infection With Cervical Squamous Intraepithelial Lesions

OBJECTIVES

Human papillomavirus (HPV) is known to be associated with squamous intraepithelial lesions (SILs). However, there is limited and conflicting literature on the relationship between bacterial vaginosis (BV) and SIL. The aim of this study is to determine the prevalence of BV and evaluate the association between BV and SIL.

METHODS

A retrospective study was performed on 10,546 cases between 2012 and 2017. HPV results were available in 7,081 cases.

RESULTS

BV was present in 17.6% of cases. There was significant association between BV, positive HPV infection, and high-grade SIL. BV patients with negative HPV infection showed more squamous abnormalities than BV-negative HPV-negative patients.

CONCLUSIONS

We found there is a significant association between BV and SIL. BV is more common among patients with HPV infection and is independently associated with squamous abnormalities in cervical smears and surgical follow-up.

Association of Trichomonas vaginalis and cytological abnormalities of the cervix in low risk women

Objective

Is Trichomonas vaginalis (TV) an inducing factor for the development of (pre-)cancerous lesions of the cervix?

Design

Cross sectional study.

Setting

Screening healthy Belgian women with low infection risk.

Sample

63,251 consecutive liquid based cervical samples.

Methods

Real time quantitative PCR for presence of TV, 18 HPV types and Pap smear analysis of cytologic abnormalities.

Main Outcome Measures

Association of TV and HPV with cervix dysplasia

Results

The overall prevalence of TV DNA was 0.37%, of low risk HPV 2%, of high risk HPV 13.2%, and 8.8 % had cytological abnormalities. Both LR-HPV and HR-HPV were significantly associated with all cytological abnormalities. Presence of TV was associated with LR- and HR-HPV, ASC-US and HSIL, but not with other abnormalities. All women with TV and HSIL also had HR-HPV, while the latter was present in only 59% of women with TV and ASC-US. Amongst HPV negative women, TV was found in 1.3% of women with ASC-US, but only in 0.03% of women with normal cytology (OR 4.2, CL95% 2.1-8.6). In HR-HPV positive women, presence of TV increased the likelihood of cytological abnormalities somewhat (P=0.05), mainly due to an increase in ASC-US and LSIL, but not HSIL.

Conclusions

We conclude that TV infection is associated with both LR and HR-HPV infection of the cervix, as well as with ASC-US and HSIL. TV is a concomitant STI, but is not thought to be a co-factor in the causation of HSIL and cervical cancer. However, TV may cause false positive diagnoses of ASC-US.

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.

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.

Distinguishing Small Cell Carcinoma From Non–Small Cell Carcinoma of the Lung: Correlating Cytologic Features and Performance in the College of American Pathologists Non-Gynecologic Cytology Program

Context.—The cytologic features of small cell carcinoma of the lung are well described. Nevertheless, some small cell carcinomas may be difficult to reproducibly distinguish from non–small cell carcinomas, and this distinction carries significant clinical importance.

Objective.—To correlate the cytologic features of individual cases of small cell carcinoma of the lung in fine-needle aspiration specimens from the College of American Pathologists Non-Gynecologic Peer Comparison Cytology Program with the frequency of misclassification as non– small cell carcinoma.

Design.—We reviewed 1185 interpretations of 23 different cases of small cell carcinoma in lung fine-needle aspiration specimens and correlated the cytologic features noted in these cases with performance in the program.

Results.—Cases were divided into those that were frequently misclassified as non–small cell carcinoma (at least 10% of the responses, 11 cases) and those that were infrequently misclassified as non–small cell carcinoma (&lt;5% of all responses, 12 cases). All cases had areas on the slides with classic features of small cell carcinoma. However, 10 of 11 cases that were frequently misclassified as non–small cell carcinoma had cells with either increased cytoplasm (4 cases), cytoplasmic globules (so-called paranuclear blue bodies) (3 cases), or apparent intracytoplasmic lumina (3 cases). These features were not identified in cases that were infrequently misclassified (P = .005). In addition, cases more frequently misclassified as non–small cell carcinoma tended to show better overall cellular and group preservation.

Conclusions.—Frequent misclassification of small cell carcinoma as non–small cell carcinoma in lung fine-needle aspiration specimens in this program correlates strongly with the presence of cytoplasmic features that may suggest non–small cell carcinoma or with the presence of paranuclear blue bodies. Misclassification in this program may reflect a variety of factors, including the variation in the cytologic features of individual cases, but also the lack of wide recognition that some features of non–small cell carcinoma may also be noted in well-preserved cases of small cell carcinoma.