Should the cytologic diagnosis of "atypical squamous cells of undetermined significance" be qualified? An assessment including comparison between conventional and liquid-based technologies

Atypical squamous cells of undetermined significance-favour reactive compared to atypical squamous cells of undetermined significance-favour dysplasia: association with cervical intraepithelial lesions and human papillomavirus infection

BACKGROUND AND OBJECTIVES

The current study compared the cervical cytological sub-category "atypical squamous cells of undetermined significance-favour reactive (AFR)", recently recommended to be eliminated by the Bethesda system, to the sub-category "atypical squamous cells of undetermined significance-favour dysplasia (ASC-US)", in terms of prevalence of coexistent squamous intraepithelial lesions of either low-grade (LSIL) or high-grade (HSIL) and rate of human papillomavirus (HPV) infection.

STUDY DESIGN

One hundred women with AFR and 100 with ASC-US were consecutively included in the study. All patients underwent colposcopy, followed by biopsy when necessary, and were screened for HPV infection by the combined use of Hybrid Capture II (DIGENE) and PCR with MY09/11 primers, the latter followed by direct sequencing of the amplifications products for HPV genotyping.

RESULTS

LSIL were detected in 5.6% of AFR and 18.5% of ASC-US (p=0.00812), HSIL only in 4.3% of ASC-US. HPV infection was diagnosed in 11.2% of AFR and 38.0% of ASC-US (p=0.00003); high-risk HPV types (namely, HPV-16, -18, -31, -66, -67 and -70) were found in 6.7% of AFR and 22.8% of ASC-US (p=0.00239). Evidence of HPV infection in absence of SIL was proven in 7.1% of AFR and in 22.5% of ASC-US (p=0.00622).

CONCLUSION

The association of AFR with SIL and high-risk HPV infection is low but not inexistent. Thus, to avoid the risk of leaving some high-risk AFR patients untreated or without follow-up, it could be proposed to keep AFR as a cytological category and to triage it by HPV testing, similarly to what has been already recommended for ASC-US.

Significance of atypia in conventional Papanicolaou smears and liquid-based cytology: a follow-up study

The diagnosis of atypical squamous epithelial cells, borderline nuclear changes, is associated with some controversy, as it encompasses benign, reactive, as well as possible neoplastic conditions. The aim of this study was to evaluate the follow-up diagnoses of cytological atypia in conventional Papanicolaou smears (CP) and liquid-based samples by the ThinPrep Pap Test (TP). A total of 1607 CP smears from 1 January 2000 to 31 December 2000 and 798 TP samples from 1 January 2002 to 31 December 2002 diagnosed as atypia were included. The results show that the detection rate of atypia in cervical cytological samples was reduced by 41.3% (P < 0.001) in TP compared with CP. Cytological and histological follow-up data showed the presence of neoplastic lesions in 34.7% of patients screened by TP versus 22.3% of patients screened by CP, corresponding to a 55.6% increase in TP (P < 0.001). Follow-up diagnosis of mild dysplasia was seen more than twice as often in TP than in CP (12.8% versus 5.0%, P < 0.001). The prevalence of moderate and severe dysplasia was significantly increased with 26.7% in TP compared with CP (21.9% versus 17.2%, P < 0.01). In conclusion, the ThinPrep Pap Test yielded a significant decrease in atypia rates compared with the conventional Papanicolaou test. In subsequent follow-up the percentage of neoplastic lesions was significantly increased in the ThinPrep Pap Test samples.

Effect of Bethesda 2001 on reporting of atypical squamous cells (ASC) with special emphasis on atypical squamous cells-cannot rule out high grade (ASC-H)

We compared the overall ASC rate and the outcomes for women with different categories of ASC before and after TBS 2001 to evaluate the impact of TBS 2001. Our laboratory reported ASC in four subcategories before TBS 2001; ASC, favor reactive (ASC-R), favor low-grade squamous intraepithelial lesion (SIL) (ASC-L), undetermined significance (ASC-US), and ASC-H. Since the implementation of TBS 2001, we have been reporting ASC as ASC-US and ASC-H. After TBS 2001, our ASC rate decreased from 6.2% to 4% (P < 0.0001). Before TBS 2001, ASC-R carried the same risk as ASC-US for underlying condyloma/CIN 1. Moreover, ASC-R was rarely associated with CIN 2 or 3. Before TBS 2001, ASC-H captured more low-grade (condyloma/CIN 1) and less high-grade (CIN 2, 3, and SCC) lesions compared to after TBS 2001. More women with ASC-H after TBS 2001 underwent colposcopy (80% vs. 71%, P < 0.05). Twenty-two percent of women with ASC-H required 2-4 colposcopies to identify the high-grade lesion. Our results confirm that consistent application of TBS 2001 terminology for ASC reduces the ASC rate, and better identifies women at high risk for CIN 2, 3, and SCC. In addition, ASC-H requires very close clinical follow-up as a significant percentage of women require more than one colposcopy to identify the high-grade lesion.

Atypical squamous cells: update on current concepts

Besides all the confusion and associated problems that the use of ASC has created, it has initiated substantial investigational interest that has resulted in a better understanding of squamous intraepithelial lesions and the biology of cervical neoplasia. Although the category of ASC has created, and will continue to create, controversy in the diagnostic and management fields, it allows the pathologist to convey uncertainty that may be the result of poor sampling or difficulty in interpretation of a case. It is a valuable tool that the cytopathologist can use to make it known that the Papanicolaou test has its limitations and may need and benefit, in some instances, from support from ancillary studies. Similar limitations are recognized in other areas of pathology and the use of immunohistochemistry or molecular studies is widely accepted as an aid to a more specific and definitive interpretation. The time for the Papanicolaou test to be considered similarly has arrived. HPV DNA testing may not be the perfect test for cervical cancer screening because of high prevalence of HPV infection in the general population; however, it is currently the best-studied ancillary test and has been proven to be cost-effective for the triage of Papanicolaou tests with equivocal squamous cells. It is important for the cytopathologist to have well-developed diagnostic skills in interpreting gynecologic preparations, and to classify cases as ASC only when deemed appropriate. Downgrading cytologic findings that are diagnostic of a squamous intraepithelial lesion to ASC with the hope of supporting it by an HPV test will only result in a devaluation of the Papanicolaou test. Such recourse may, however, be acceptable in specific situations, such as in patients who have complex histories, atypical clinical presentations, or during pregnancy. Quality assurance measures to closely monitor the ASC:SIL ratio and the rate of HPV positivity in ASC cases will be essential to ensure the appropriate use of this interpretive category. The coordination of the 2001 Bethesda and ASCCP consensus meetings resulted in the new subcategories of ASC-US and ASC-H, along with well-defined management strategies for these interpretations. This new and clinically relevant terminology should lead to a reduction in difficulties at the clinical level and a more uniform management of patients, unlike the situation following Bethesda 1991 where the gynecologist was faced with a new "diagnosis" without specific management recommendations. The standardization of reporting and clinical management will also allow more reliable evaluation of patient outcomes and cost analysis. The 2002 American Cancer Society guidelines did not make specific recommendations regarding HPV DNA testing for the triage of patients who have a cytology result of ASC-US [64]. The FDA approved the expanded use of HPV testing in conjunction with the Papanicolaou test for cervical cancer screening in March of 2003. The future is likely to bring additional testing modalities that may be more specific for detecting squamous lesions that are more likely to persist or progress to carcinoma, than the currently available HPV tests. In addition, looking to the more distant future, recently published data from HPV vaccine trials suggests that immunizing women who are negative for HPV-16 may eventually reduce the incidence of cervical cancer [65]. At the present, however, the most effective method to decrease the mortality of this disease process is to make sure that all women have access to, and receive, effective cervical cytologic screening.

Oral contraceptive pills are associated with artifacts in ThinPrep Pap smears that mimic low-grade squamous intraepithelial lesions

BACKGROUND

The authors noted a significant increase in the diagnosis of atypical squamous cells of undetermined significance (ASCUS) in premenopausal women using oral contraceptive pills (OCP) (9%) versus women not on OCP (4%) using ThinPrep Pap smears (P = 0.02). The purpose of this study was to correlate these morphologic changes with human papillomavirus (HPV) DNA detection by in situ hybridization and clinical follow-up.

METHODS

Eighty-four ThinPrep Pap smears diagnosed as ASCUS or ASCUS favor low-grade squamous intraepithelial lesions (LGSIL) in young women receiving OCP were studied by HPV in situ hybridization. This information was correlated with colposcopic follow-up and AutoCyte Pap smear results. The authors also studied 80 ThinPreps from young women with a Pap smear diagnosis of unequivocal LGSIL where there was a corresponding biopsy (positive controls) and 40 ThinPreps diagnosed as within normal limits and that rescreened as such (negative controls).

RESULTS

The detection rate of HPV DNA by in situ hybridization was 33% (28 of 84) in ASCUS cases versus 90% (72 of 80) for cases of unequivocal LGSIL. A blinded review of the 29 ASCUS Pap smears performed by AutoCyte showed that 66% (19 of 29) were diagnosed as within normal limits. The majority of the cervical biopsies in the women with ASCUS by ThinPrep Pap smears were negative for dysplasia (29 of 39 [74%]) whereas 71 of 80 biopsies (88%) showed dysplasia in women with Pap smears diagnosed as unequivocal LGSIL. The periodic acid-Schiff (PAS) stain demonstrated that many of the cells with halos in the ThinPrep Pap smears that mimicked LGSIL contained glycogen.

CONCLUSION

The ThinPrep induces changes that mimic LGSIL in young women on OCP. These artifacts may reflect pressure-induced alteration of glycogen. PAS analysis and, more directly, HPV testing by in situ hybridization can help differentiate this mimicking from actual LGSILs.

Borderline nuclear change; can a subgroup be identified which is suspicious of high-grade cervical intraepithelial neoplasia, i e CIN 2 or worse?

Borderline nuclear change; can a subgroup be identified which is suspicious of high-grade cervical intraepithelial neoplasia, i.e. CIN 2 or worse? Only 10% of first borderline smears are associated with a histological high-grade (HG) abnormality, i.e. CIN 2,3, invasive malignancy or glandular neoplasia on subsequent investigation. The advantages of highlighting this subgroup are obvious but is this possible? From 1996 and 1997, 242 borderline smears with histological follow-up were examined by two independent experienced observers (observer 1 and 2) without prior knowledge of further investigation results. For each smear a profile of nuclear details was produced, also noting the type of cell mainly affected by the process; then the observers were asked to assess the degree of worry of HG disease for each smear i.e. whether the smear fell into group 1 borderline changes indicative of low-grade (normal, inflammatory, CIN1/HPV) disease (BL/LG) or group 2 difficult borderline smear, HG disease (CIN 2,3, invasive neoplasia or glandular neoplasia) cannot be excluded (BL/HG). Observer 1 selected a group of BL/HG with a PPV for HG disease of 38%, with observer 2 having a PPV of 50%; this compared with the overall laboratory HG disease PPV for borderline smears of 14%. Both observers found the most useful criterion to be the increase in nuclear:cytoplasmic ratio. Our results show that it is possible to separate a small group of borderline smears which should be classified as 'borderline/high grade lesion difficult to exclude' (BL/HG). Both observers had some success in arriving at this classification although their method of selecting out this group was quite different.