The utility of p16INK4a and Ki-67 staining on cell blocks prepared from residual thin-layer cervicovaginal material

Quality of cell blocks prepared from residual pleural effusion and bronchial washing samples for immunocytochemistry

INTRODUCTION

Cell blocks (CBs) enable the long-term preservation of cytological samples. The aim of this study was to analyse the quality of CBs prepared from leftover fluid from lung adenocarcinoma pleural effusion samples and residual bronchial washing sediment for immunocytochemistry.

METHODS

The residual part of 455 lung adenocarcinoma pleural effusion samples and sediment from 384 bronchial washing samples were used to prepare CBs following the agarose method. The quality of CBs was evaluated based on the quantity of malignant cells in haematoxylin and eosin-stained slides and interpreted as optimal or insufficient for immunocytochemistry. Immunocytochemistry on CBs was performed using the Dako EnVision™ FLEX detection visualisation system. The CB results for TTF-1, ALK, and PD-L1 immunocytochemistry were compared with the corresponding cytological smears.

RESULTS

Among all CBs, 202 (44.4%) from leftover pleural effusion fluid and 85 (22.1%) from residual bronchial washing sediment had an optimal number of lung adenocarcinoma cells. Eight pleural effusion CBs were stained for TTF-1. Four pleural effusion and two bronchial washing CBs were stained for ALK and PD-L1. All tested pleural effusion CBs were confirmed positive for TTF-1 and negative for ALK. The PD-L1 tumour proportion score (TPS) was ≥ 50% in two pleural effusions. ALK was confirmed negative in bronchial washing CBs. One bronchial washing CB was interpreted as PD-L1-negative while the corresponding smear was positive (TPS ≥1%; 2%).

CONCLUSION

The CB results of TTF-1, ALK, and PD-L1 corresponded to the findings for the smears. The inclusion of CBs prepared from leftover fluid from pleural effusion samples and residual bronchial washing sediment in routine cytological practice could provide a source of high-quality material for immunocytochemistry in addition to smears and cytospins.

Immunocytochemistry for diagnostic cytopathology-A practical guide

Cytological specimens, which are obtained by minimally invasive methods, are an excellent source of diagnostic material. Sometimes they are the only material available for diagnosis as well as for prognostic/predictive markers. When cytomorphology is not straightforward, ancillary tests may be required for a definitive diagnosis to guide clinical management. Immunocytochemistry (ICC) is the most common and practical ancillary tool used to reach a diagnosis when cytomorphology is equivocal, to differentiate entities with overlapping morphological features, and to determine the cell lineage and the site of origin of a metastatic neoplasm. Numerous immunomarkers are available, and some are expressed in multiple neoplasms. To rule out entities within a differential diagnosis, the use of more than one marker, sometimes panels, is necessary. ICC panels for diagnostic purposes should be customised based on the clinical context and cytomorphology, and the markers should be used judiciously to preserve material for additional tests for targeted therapies in the appropriate setting. This review offers a practical guide for the use of ICC for diagnostic cytopathology, covering the most commonly encountered non-hematolymphoid diagnostic scenarios in various body sites.

Architectural aspects of cell-blocks as small biopsies

Cell-block preparations have become an essential part of integrated cytology diagnosis. They are essentially microbiopsies that are formalin fixed and embedded in paraffin. This has become more prevalent with greater sample procurement due to the advent of newer biopsy techniques and needles. Cell-blocks allow retrieval of small tissue fragments from cytology specimens that sometimes cannot be processed by alternate cytologic techniques. They represent concentrated, cell-enriched preparations that provide cytologists with the opportunity to evaluate cellular architecture, as well as to perform ancillary testing. A cell-block compatible sample may thus obviate the need for a more invasive procedure such as a tissue biopsy. Microscopic examination of cell-blocks is quick, avoids obscuring material, permits cells to be evaluated in one focal plane, and allows the histologic architecture such as glandular differentiation, papillary formations, and sometimes invasion to be easily identified. This new era of “cytohistology” accordingly requires practicing cytologists to become more familiar with histopathology. This review article discusses the benefit of various architectural patterns identifiable in cell-blocks employed as an adjunct to Pap tests, exfoliative fluid specimens, and fine-needle aspirations.

Evaluation of p16INK4a immunostaining for the detection of high-grade changes in cervical cytology

Since its introduction in Australia in 2007, the human papillomavirus (HPV) vaccine has led to a markedly lower prevalence of vaccine targeted HPV genotype infections as well as HPV disease including genital warts and histologically confirmed high-grade (HG) cervical abnormalities. To increase the ability to identify abnormal cells in lower prevalence, adjunct markers can be incorporated to improve the sensitivity and specificity of cytology test. One such marker is p16(p16), which is detectable in cells expressing the E7 oncogene encoded by high-risk HPVs (HR-HPV). In this study, the sensitivity and specificity of p16 immunostaining in detection of underlying HG lesions was evaluated in a cohort of 454 women undergoing surgical treatment for biopsy proven cervical dysplasia. Overall, p16 positive cells were detected in 321 (71%) of cytology preparations evaluated. Comparison of p16 staining on cytological preparations to histology diagnosis available on 212 patients, showed 26 (54%), 41 (78%) and 80 (90%) of cytology preparations to be p16 positive in women with CIN1, CIN2 and CIN3, respectively (p < 0.005). HPV16 and 18 were the most prevalent genotypes in HG lesions and were highly correlated with p16 staining. p16 staining provides an additional marker which can assist in better detecting underlying HG lesion in cytology smears with low disease prevalence.

Cell blocks in cytopathology: a review of preparative methods, utility in diagnosis and role in ancillary studies

The cell block (CB) is a routine procedure in cytopathology that has gained importance because of its pivotal role in diagnosis and ancillary studies. There is no precise review in the published literature that deals with the various methods of preparation of CB, its utility in diagnosis, immunocytochemistry (ICC) or molecular testing, and its drawbacks. An extensive literature search on CB in cytology using internet search engines was performed for this review employing the following keywords: cell block, cytoblock, cytology, cytopathology, methods, preparation, fixatives, diagnostic yield, ancillary and molecular studies. Ever since its introduction more than a century ago, the CB technique has undergone numerous modifications to improve the quality of the procedure; however, the overall principle remains the same in each method. CBs can be prepared from virtually all varieties of cytological samples. In today's era of personalized medicine, cytological specimens, including CBs, augment the utility of cytological samples in analysing the molecular alterations as effectively as surgical biopsies or resection specimens. With the availability of molecular targeted therapy for many cancers, a large number of recent studies have used cytological material or CBs for molecular characterization. The various techniques of CB preparation with different fixatives, their advantages and limitations, and issues of diagnostic yield are discussed in this review.

p16 INK4a and Ki67 expression in normal, dysplastic and neoplastic uterine cervical epithelium and human papillomavirus (HPV) infection

Cellular cycle proteins like the p16(INK4a) and the Ki67 proliferation nuclear antigen have been used as oncogenicity cellular markers. The E6 and E7 oncoproteins interact with tumor suppressor genes p53 and pRb, culminating with the p16(INK4a) overexpression. The objective of this study was to evaluate the presence of HPV-DNA in 174 cervical biopsies and correlate the different histological grades with the p16(INK4a) and Ki67 immunohistochemical expression (IHC). A cross-sectional study that enrolled a total of 174 women who underwent uterine cervical biopsies between February 2003 and December 2006, in southern Brazil, was performed. Cervical smear samples were analyzed for the presence of HPV-DNA through polymerase chain reaction (PCR), and biopsy samples were examined for p16(INK4A) and Ki67 expression through IHC techniques. The presence of HPV-DNA was observed in 89% of the tested patients, among which 52% were positive for high-risk (HR) viral types [16, 18 and 31]. Regarding p16(INK4a), an expression of 69% was observed, being expressed in 100% of the high-grade squamous lesions (HSIL) and HR-HPV-DNA positives. Ki67 expression was associated with the lesion grade, being more expressive in the most severe lesions (p<0.001). p16(INK4A) and Ki67 markers coexpression was present in 86% of the samples (p<0.001), being 100% among those positive to HR-HPV-DNA with HSIL (p<0.001). The results suggest an association between the presence of HR-HPV infection and the p16(INK4a) and Ki67 expression and which is even stronger among women with HSIL.

Utility of P16 expression and Ki-67 proliferation index in ASCUS and ASC-H pap tests

Current cervical screening uses a combination of cytology and high-risk human papillomavirus (HR-HPV) analysis in cases of atypical squamous cells of undetermined significance (ASCUS) and atypical squamous cells cannot exclude high-grade intraepithelial lesion (ASC-H). These diagnoses are subject to interobserver variability and HR-HPV analysis can be limited by sampling inadequacy. This study correlates immunoexpression of P16 and Ki-67 in residual cervicovaginal material against cytology category and HR-HPV status. Eighteen pap tests were selected: 8 ASCUS, 4 ASC-H, and 6 controls (2 LSIL and 4 HSIL). Digene Hybrid Capture II test was used to detect HR-HPV. The cytospins were stained for P16/Ki-67. Pap tests, P16, Ki-67, HR-HPV result and available biopsies were correlated. P16 expression correlated with HR-HPV status in 15/17 cases. Discordant cases (1 ASCUS and 1 ASC-H) were +P16/-HR-HPV. Ki-67 correlated with HR-HPV in 8/15 cases. Discordant cases were +HR-HPV/- Ki-67 (HSIL, LSIL, and ASC-H one each), and -HR-HPV/+Ki-67 (3 ASCUS, 1 LSIL, 1 ASC-H). Two cases were + P16/+ Ki-67/- HR-HPV. None were - P16/- Ki-67/+ HR-HPV. Histologic follow-up in 13 cases varied from benign to CIN III. Two cases of +P16/ - Ki-67/- HR-HPV had benign cervical biopcies. Although a small sample size, our findings show a utility for adjunct P16/ Ki-67 in addition to HR-HPV testing in cases of squamous atypia when HR-HPVs are non-detected due to low DNA copies, or missed lesions in cervical biopsies.

p16 immunocytochemistry on cell blocks as an adjunct to cervical cytology: Potential reflex testing on specially prepared cell blocks from residual liquid-based cytology specimens

Background:

p16 ^INK4a (p16) is a well-recognized surrogate molecular marker for human papilloma virus (HPV) related squamous dysplasia. Our hypothesis is that the invasive interventions and related morbidities could be avoided by objective stratification of positive cytologic interpretations by p16 immunostaining of cell block sections of cytology specimens.

Materials and Methods:

Nuclear immunoreactivity for p16 was evaluated in cell block sections in 133 adequate cases [20 negative for intraepithelial lesion or malignancy, 28 high-grade squamous intraepithelial lesion (HSIL), 50 low-grade squamous intraepithelial lesion (LSIL), 21 atypical squamous cells, cannot exclude HSIL (ASC-H), and 14 atypical squamous cells of undetermined significance (ASCUS)] and analyzed with cervical biopsy results.

Results:

(a) HSIL cytology (28): 21 (75%) were p16 positive (11 biopsies available — 92% were positive for cervical intraepithelial neoplasia (CIN) 1 and above) and 7 (25%) were p16 negative (3 biopsies available — all showed only HPV with small atypical parakeratotic cells). (b) LSIL cytology (50): 13 (26%) cases were p16 positive (12 biopsies available — all were CIN1 or above) and 37 (74%) were p16 negative (12 biopsies available — all negative for dysplasia. However, 9 (75%) of these biopsies showed HPV). (c) ASC-H cytology (21): 14 (67%) were p16 positive (6 biopsies available — 5 showed CIN 3/Carcinoma in situ/Ca and 1 showed CIN 1 with possibility of under-sampling. Cytomorphologic re-review favored HSIL) and 7 (33%) were p16 negative (5 biopsies available — 3 negative for dysplasia. Remaining 2 cases — 1 positive for CIN 3 and 1 showed CIN 1 with scant ASC-H cells on cytomorphologic re-review with possibility under-sampling in cytology specimen). (d) ASCUS cytology (14): All (100%) were p16 negative on cell block sections of cervical cytology specimen. HPV testing performed in last 6 months in 7 cases was positive in 3 (43%) cases.

Conclusion:

p16 immunostaining on cell block sections of cervical cytology specimens showed distinct correlation patterns with biopsy results. Reflex p16 immunostaining of cell blocks based on the algorithmic approach to be evaluated by a multiinstitutional comprehensive prospective study is proposed.

Comparison of p16INK4a and ProEx C immunostaining on cervical ThinPrep cytology and biopsy specimens

ProEx C and p16(INK4a) staining of cytology/histology specimens have recently been explored to help distinguish high-grade squamous intraepithelial lesions (HSIL) from benign mimics. The goal of this study was to evaluate the performance characteristics of p16 and ProEx C in tissue and patient matched ThinPrep liquid-based cytology specimens. Residual cervical ThinPrep cytology specimens and tissue blocks (N = 64) from 63 patients were stained with p16 and ProEx C. Review of immunostained material, Papanicolaou and H&E stained slides was performed by two cytopathologists. The cytology slides were evaluated for the presence or absence of squamous atypia as well as immunoreactivity. Histologic specimens were interpreted as negative, indeterminate, or positive for each immunostain. There was 86% agreement (55/64) between the p16 and ProEx C stains on tissue specimens. Eleven specimens were interpreted as positive for both stains. All had a low- or high-grade squamous lesion on the corresponding H&E section. ProEx C was able to identify four low-grade squamous intraepithelial lesion specimens that were interpreted as negative by p16. All four HSIL specimens demonstrated p16 and ProEx C staining. However, 84% of cytology negative specimens demonstrated false-positive staining. Clinical utilization of both stains, combined with morphologic features, may be beneficial for confirming HSIL on histologic specimens. ProEx C and/or p16 immunostains may lead to a false-positive result in cytology specimens due to staining of normal appearing cells.

Diagnostic value of p16INK4A, Ki-67, and human papillomavirus L1 capsid protein immunochemical staining on cell blocks from residual liquid-based gynecologic cytology specimens

BACKGROUND

This study was conducted to evaluate the reliability and role of cell block preparations in the diagnosis of neoplastic and preneoplastic lesions of the cervix and to improve the value of cell block preparations in diagnosing and predicting the prognosis of cervical lesions through immunostaining of p16INK4A (p16), Ki-67, and human papillomavirus (HPV) L1 capsid protein (HPV L1).

METHODS

In total, 138 specimens were diagnosed on liquid-based cytology (LBC) and cell block preparations, and 63 specimens were subjected subsequently to tissue follow-up and immunostaining for p16, Ki-67, and HPV L1 on cell block sections.

RESULTS

In 42 specimens that were diagnosed as low-grade squamous intraepithelial lesion, high-grade squamous intraepithelial lesion (HSIL), and squamous cell carcinoma (SCC) on cell blocks, 38 specimens (90.5%) were confirmed by histopathologic reports, and there was slightly better than 81.6% agreement between LBC and tissue follow-up. Immunointensity and cells that were positive for p16 were enhanced according to increased pathologic grade and differed statistically between cervical intraepithelial neoplasia 1 (CIN-1) and CIN-2/CIN-3 as well as SCC. The positive rates of HPV L1 decreased gradually according to the severity of cervical neoplasia, and HPV L1/p16 expression patterns were related to the severity of cervical lesions.

CONCLUSIONS

The cell block preparation technique was complementary to LBC, and the authors concluded that the application of LBC combined with cell block preparations may improve the diagnostic accuracy of cytology. Immunostaining for p16 and Ki-67 on cell block preparations can help to improve the diagnostic accuracy of HSIL and SCC. A combined expression pattern of p16 and HPV L1 may serve as a valuable index for predicting prognosis and follow-up of cervical dysplastic lesions.

The diagnostic utility of cell blocks prepared from residual SurePath Pap material for detection of human papilloma virus

This study was undertaken to determine if tissue sections from cell block prepared from the residual cellular sediment of Pap test vials could be used for immunohistochemistry (IHC) or in situ hybridization (ISH) for the detection of human papilloma virus (HPV) and to determine if these stains could clarify the nature of atypical cases in certain cases. Cases included in this retrospective study are categorized into 3 groups. Group 1 included 12 positive and 10 negative cases that were used to optimize the IHC and ISH staining protocol for the detection of HPV. Cases selected in group 2 were included to validate and verify the IHC and ISH stains. We validated 20 negative and 37 positive cases. Group 3 included 37 atypical cases. Unused material from the corresponding liquid-based (SurePath) Pap test specimens were retrieved and used to prepare paraffin-embedded cell blocks. Hematoxylin and eosin-stained cell-block sections were evaluated for abnormal cells. The IHC and ISH stain protocols for detection of HPV DNA were successfully optimized, validated, and verified. The sensitivity for the detection of HPV DNA using IHC in atypical squamous cells of undetermined significance was 80% and in atypical squamous cell, cannot rule out high grade, was 78% whereas the specificity was 100% in both lesions. Both the sensitivity and specificity for the detection of HPV DNA using the ISH were 100%. This study demonstrated that cell-block sections prepared from residual SurePath Pap test material could be used for detection of HPV DNA by both IHC and ISH and clarify the nature of atypical cells on cell-block sections.

p16(INK4a) immunostaining in cytological and histological specimens from the uterine cervix: a systematic review and meta-analysis

BACKGROUND

P16(INK4a) is a biomarker for transforming HPV infections that could act as an adjunct to current cytological and histological assessment of cervical smears and biopsies, allowing the identification of those women with ambiguous results that require referral to colposcopy and potentially treatment.

MATERIAL AND METHODS

We conducted a systematic review of all studies that evaluated the use of p16(INK4a) in cytological or histological specimens from the uterine cervix. We also estimated the mean proportion of samples that were positive for p16(INK4a) in cytology and histology, stratified by the grade of the lesion.

RESULTS

Sixty-one studies were included. The proportion of cervical smears overexpressing p16(INK4a) increased with the severity of cytological abnormality. Among normal smears, only 12% (95% CI: 7-17%) were positive for the biomarker compared to 45% of ASCUS and LSIL (95% CI: 35-54% and 37-57%, respectively) and 89% of HSIL smears (95% CI: 84-95%). Similarly, in histology only 2% of normal biopsies (95% CI: 0.4-30%) and 38% of CIN1 (95% CI: 23-53%) showed diffuse staining for p16(INK4a) compared to 68% of CIN2 (95% CI: 44-92%) and 82% of CIN3 (95% CI: 72-92%).

CONCLUSION

Although there is good evidence that p16(INK4a) immunostaining correlates with the severity of cytological/histological abnormalities, the reproducibility is limited due to insufficiently standardized interpretation of the immunostaining. Therefore, a consensus needs to be reached regarding the evaluation of p16(INK4a) staining and the biomarker needs to be assessed in various clinical settings addressing specific clinical questions.

Comparison of ProEx C with p16INK4a and Ki-67 immunohistochemical staining of cell blocks prepared from residual liquid-based cervicovaginal material: a pilot study

BACKGROUND

Although liquid-based cervicovaginal cytology has high sensitivity for detecting dysplastic/malignant lesions, many pitfalls exist. Cell blocks can be prepared from residual liquid-based cervicovaginal material and used for immunohistochemistry. The aim of this study was to evaluate a new marker, ProEx C, on cell blocks and its ability to distinguish dysplastic/malignant lesions from morphologically abnormal but benign cells. The results of this study were compared with previously reported results for p16 and Ki-67 on the same material.

METHODS

ProEx C is a cocktail of monoclonal antibodies against proteins associated with aberrant S phase cell cycle induction (topoisomerase IIA, minichromosome maintenance protein 2). ThinPrep (CytycCorp., Boxborough, Mass) cervicovaginal specimens from 79 patients were selected. Four cases had no residual abnormal cells in the cell block. On the basis of the cell block diagnosis, 29 cases were negative for intraepithelial lesion or malignancy (NILM), 27 had low-grade squamous intraepithelial lesions (LSIL), 16 had high-grade squamous intraepithelial lesions (HSIL), and 3 had squamous cell carcinomas (SCC). Cell block sections were immunostained with ProEx C.

RESULTS

Thirteen of 16 (81%) cases of HSIL stained positively with ProEx C. Two of 27 (7%) LSIL stained positively, and 2 (7%) cases of NILM stained positively. All 3 cases of SCC were strongly positive (100%). Staining for ProEx C showed a higher positive predictive value compared with p16.

CONCLUSIONS

ProEx C can be used on cell blocks prepared from residual liquid-based cervicovaginal cytologic specimens. Being a nuclear only stain, it is cleaner and easier to interpret even in scant specimens.

Human papillomavirus mRNA and p16 detection as biomarkers for the improved diagnosis of cervical neoplasia

Human papillomavirus (HPV) infection of the genital tract is very common and normally follows a benign clinical course; however, in an unfortunate minority of infected individuals, it can cause disease that sometimes leads to cancer. It is accepted that HPV DNA testing has a role in the management of cervical disease both in a prevaccination and postvaccination era; however, to improve the specificity of this approach, there is a requirement to develop and validate tools/assays that can identify women at risk for progressive disease. There is evidence to suggest that detection of viral gene expression both directly and indirectly may constitute a more specific approach for delineating clinically significant infection compared with HPV DNA-based assays. HPV oncogene expression and evidence of its deregulation can be monitored through direct detection of viral mRNA transcripts or through detection of the cellular protein p16. For both approaches, commercial assays have been introduced and numerous studies have been conducted. The present article describes the scientific theory underpinning these approaches, their amenability to routine-diagnostic specimens/settings, and the clinical data that has been garnered through their application thus far. Currently, there is promising data indicating that HPV mRNA and p16 might play an important role in future cervical cancer screening scenarios. Still, large randomized studies are necessary to confirm the preliminary data.

METHODS

PubMed and OVID were interrogated with search terms "HPV RNA;" "HPV mRNA;" "HPV transcript-detection, testing, and methods;" "p16" AND "cervical cancer;" "p16" AND "CIN;" "p16" AND "histology"; "p16" AND "cytology;" "p16;" and "screening."

Biomarker (ProEx C, p16(INK4A), and MiB-1) distinction of high-grade squamous intraepithelial lesion from its mimics

Topoisomerase IIalpha and minichromosome maintenance protein 2 are proteins associated with aberrant S-phase induction. The current study evaluated the performance of these biomarkers (ProEx C; TriPath Oncology, Burlington, NC) compared with p16(INK4A) and MiB-1 in distinguishing high-grade squamous intraepithelial lesions (HSILs) from HSIL mimics. We collected archival cervical biopsy, cone, and curettage specimens from 96 cases in which the differential diagnosis of HSIL vs reactive epithelial changes was considered. Hematoxylin- and eosin-stained slides were reviewed independently by three pathologists and scored for the presence or absence of SIL. Immunostains for ProEx C, p16, and MiB-1 were available for 95, 96, and 59 samples, respectively, and classified blinded to histological interpretation. Strong nuclear and cytoplasmic staining for p16 and staining for MiB-1 and ProEx C that extended beyond the lower one-third of the epithelium were scored as positive. Chi(2)-tests and receiver operating characteristic analysis were conducted to statistically compare biomarker immunostaining performance against majority histological interpretation of SIL. Agreement between pathologists was also assessed by the kappa-statistic. Inter-observer agreement ranged from fair to moderate (kappa=0.37-0.57). All three biomarkers correlated strongly with the majority diagnosis of SIL (P<0.001). Positive staining for ProEx C, p16, and MiB-1 was observed in 87% (N=52/60), 84% (N=51/61), and 94% (34/36), respectively, of SIL and negative in 71% (N=25/35), 63% (N=22/35), and 52% (N=12/23), respectively, of majority diagnoses of NoSIL. The combination of p16/ProEx C predicted more SIL (92%, N=33/36) and NoSIL (61%, N=14/23) than p16 plus MiB-1 (94%, N=34/36 and 43%, N=10/23), although this difference was not statistically significant. ProEx C appears to provide an equivalent level of sensitivity and a higher level of specificity for HSIL alone or in conjunction with p16. Its principal value may be in providing a lower false positive rate for NoSIL relative to MiB-1.

Are adjunctive markers useful in routine cervical cancer screening? Application of p16(INK4a) and HPV-PCR on ThinPrep samples with histological follow-up

The objectives of the study were to evaluate 1) the diagnostic sensitivity and specificity of p16(INK4a) as a marker for high-grade cervical lesions, 2) the results of a real-time polymerase chain reaction detecting high-risk human papillomavirus, and 3) the interobserver variability of the p16(INK4a) interpretation.A total of 232 ThinPrep samples were stained for p16(INK4a), and HPV-DNA PCR was performed on 107 specimens with inclusion of both benign and abnormal cytology. Histological follow-up information was collected. The diagnostic sensitivity of ASC+ with CIN2+ in histology as endpoint was 96% for p16(INK4a) and 100% for HR-HPV DNA PCR, and the diagnostic specificity was 41% and 27%, respectively. If p16(INK4a) had been used for triage of the ASC samples, then 18 patients (42%) could have been spared unnecessary follow-up procedures compared to six patients (21%) with the HR-HPV DNA test.

Longitudinal clinical evaluation of a novel antibody cocktail for detection of high-grade squamous intraepithelial lesions on cervical cytology specimens

CONTEXT

Although cervical cancer screening by cytology is successful, the test continues to show relatively poor operating characteristics. Cell cycle markers may enhance detection of high-grade squamous intraepithelial lesions.

OBJECTIVE

To determine the clinical usefulness of ProExC, an immunocytochemical assay for cell cycle components, performed on routine cervical cytology samples.

DESIGN

Cervical cytology samples were collected using the SurePath method. Residual cells remaining after preparation of the Papanicolaou-stained slide were used to make a second slide for ProExC staining using an indirect polymer-based immunoperoxidase method. Only adequately cellular slides were evaluated for the presence of nuclear staining within cytologically abnormal epithelial cells. Results were correlated with clinical follow-up.

RESULTS

Six hundred twenty-four samples were satisfactorily cellular and stained. Correlation with clinical follow-up for subsequent cervical intraepithelial neoplasia 2+ on biopsy/high-grade squamous intraepithelial lesion on cytology (CIN 2+/HSIL) showed that 434 results were true negative, 78 true positive, 18 false-negative, and 94 false-positive, resulting in a sensitivity/specificity of 81%/82%. When ProExC results were combined with any level of cytologic atypia, sensitivity for CIN 2+/HSIL was 92% and specificity was 84%.

CONCLUSIONS

ProExC shows promise as an aid in enhancing the sensitivity and specificity of cervical cytology for subsequent CIN 2+/HSIL and may be useful in identifying those cervical lesions most apt to progress.

Evaluation of p16INK4a as a diagnostic tool in the triage of Pap smears demonstrating atypical squamous cells of undetermined significance

BACKGROUND

P16(INK4a) (p16) has emerged as a biomarker for the detection of high-risk human papillomavirus (HR-HPV) in Papanicolaou (Pap) smears. Many studies have confirmed a strong correlation between p16 immunohistochemical positivity and high-grade squamous intraepithelial lesions (HSIL) of the cervix. Because p16 is predictive of HR-HPV and HSIL, it seems plausible that p16 could be used as a diagnostic tool to triage atypical squamous cells of undetermined significance (ASCUS) Pap smears. In this way, Pap smears with no p16 staining could be recategorized as negative for intraepithelial lesion or malignancy (NILM) before final case disposition, thus preventing unnecessary and costly follow-up.

METHODS

p16 immunostains were performed on 178 ThinPrep (Cytyc, Marlborough, Mass) Pap smears signed out as ASCUS among 5 cytopathologists. p16 stains were independently scored between 0 (no staining) and 4 (staining in cells with nuclear aberration) by either 2 or 3 pathologists. The p16 score was compared with both Hybrid Capture 2 (hc(2)) (Digene, Gaithersburg, Md) and follow-up (Pap smear and tissue) results.

RESULTS

The sensitivity and specificity of p16 immunohistochemistry compared with both hc(2) and follow-up were not statistically significant, with both data subsets having P-values greater than .05.

CONCLUSIONS

Statistical significance was not demonstrated in any of the data subsets, indicating that the p16 score alone cannot be used to recategorize Pap smears from ASCUS to NILM as a means to prevent unnecessary and expensive follow-up. Although not meeting criteria for statistical significance, the sensitivity and positive predictive value of p16 scores versus tissue follow-up only were more statistically favorable, suggesting that p16 has better correlation with tissue follow-up than results of hc(2). In addition, p16 staining was identified consistently in atrophic Pap smears, including 23 of 25 additional NILM atrophic smears stained, indicating that p16 cannot be used as a marker to triage atypical atrophic smears.

[Interest of new biomarkers in cervical precancerous lesion management]

The difficulties of cytological identification of abnormal cells, especially in case of "minor atypias", have led to search for new markers able to make cytological screening more sensitive without decrease of specificity. To date, p16 seems to be the most interesting one. It is currently used in immunohistochemistry on cervical biopsies to distinguish immature metaplasias from high-grade lesions. In cytology, its interest is not yet well defined. According to recent papers, p16 overexpression could improve the efficacy of cytological diagnosis. Further studies are required to make positive recommendations.

Cell block as an adjunct to conventional Papanicolaou smear for diagnosis of cervical cancer in resource-limited settings

OBJECTIVE

To assess the utility of indigenously prepared cell blocks (CBs) as an adjunct to a conventional smear test in providing a reliable diagnosis of clinically suspicious cervical cancer in resource-limited settings.

METHODS

Eighty-six clinically suspicious cervical cancer cases underwent a conventional smear test, CB preparation from residual cellular samples and biopsies at the same sitting. Correlations were performed between these modalities in order to derive the sensitivity and specificity of the CB technique to diagnose cervical cancer.

OBSERVATION & RESULTS

Out of 86 clinically suspicious cervical cancers, 72 (83.7%), 70 (81.4%) and 67 (77.9%) cases were diagnosed as malignant on tissue biopsies, CBs and smears respectively. CB-biopsy agreement in the diagnosis of malignancy was feasible in 87.5% of the cases while CB-Pap smear agreement was feasible in 92.5% of the cases. Sensitivity and specificity of CB preparation to diagnose malignancy was 92.5% and 100%, respectively, when the smear was taken as the reference test (excluding the unsatisfactory smears). When biopsy was taken as the gold standard, the sensitivity and specificity of CBs were 87.5% and 100% respectively (excluding the unsatisfactory biopsies). In 8/19 cases where the smear diagnoses were either unsatisfactory or atypical squamous cells/atypical glandular cells, CBs picked up malignant lesions.

CONCLUSION

CBs prepared from the residual cellular sample of conventional cervical scrapes augment the sensitivity of the smear test. When used as an adjunct to the smear, CBs aid in providing a reliable diagnosis of cervical cancer in the majority of the clinically suspected cases and thus the biopsy load can be reduced significantly in resource-poor settings.

Should LSIL with ASC-H (LSIL-H) in cervical smears be an independent category? A study on SurePath specimens with review of literature

Background

Cervical smears exhibiting unequivocal features of 'low grade squamous intraepithelial lesion' (LSIL) are occasionally also admixed with some cells suspicious for, but not diagnostic of, 'high grade squamous intraepithelial lesion' (HSIL). Only a few studies, mostly reported as abstracts, have evaluated this concurrence. In this study, we evaluate the current evidence that favors a distinct category for "LSIL, cannot exclude HSIL" (LSIL-H), and suggest a management algorithm based on combinations of current ASCCP guidelines for related interpretations.

Methods

We studied SurePath™ preparations of cervical specimens from various institutions during one year period. Cytohisto correlation was performed in cases with cervical biopsies submitted to our institution. The status of HPV DNA testing was also noted in some LSIL-H cases with biopsy results.

Results

Out of 77,979 cases 1,970 interpreted as LSIL (1,523), LSIL-H (146), 'atypical squamous cells, cannot exclude HSIL' (ASC-H) (109), and HSIL (192) were selected. Concurrent biopsy results were available in 40% (Total 792 cases: 557 LSIL, 88 LSIL-H, 38 ASCH, and 109 HSIL). Biopsy results were grouped into A. negative for dysplasia (ND), B. low grade (HPV, CIN1, CIN1 with HPV), and C. high grade (CIN 2 and above).

The positive predictive values for various biopsy results in relation to initial cytopathologic interpretation were: a. LSIL: (557 cases): ND 32% (179), low grade- 58% (323), high grade- 10% (55); b. LSIL-H: (88 cases): ND 24% (21), low grade- 43% (38), high grade- 33% (29); c. ASCH: (38 cases): ND 32% (12), low grade- 37% (14), high grade- 31% (12); d. HSIL (109 cases): ND 5% (6), low grade 26% (28), high grade 69% (75). The patterns of cervical biopsy results in cases reported as LSIL-H were compared with that observed in cases with LSIL, ASC-H, and HSIL.

94% (32 of 34) of LSIL-H were positive for high risk (HR) HPV, 1 was negative for HR HPV but positive for low risk (LR), and 1 LSIL-H was negative for HR and LR both.

Conclusion

LSIL-H overlapped with LSIL and ASC-H, but was distinct from HSIL. A management algorithm comparable to ASC-H and HSIL appears to be appropriate in LSIL-H cases.

Immunohistochemical detection of p16INK4a in liquid-based cytology specimens on cell block sections

BACKGROUND

Colposcopy biopsy procedure is a standard recommendation for atypical squamous cell cannot exclude high-grade lesion (ASC-H) in abnormal Papanicolaou smears. p16 (p16INK4a), a cell cycle regulator, has been shown to be overexpressed in squamous dysplasia. To further improve the diagnostic accuracy of the ASC-H Papanicolaou smear and to reduce unnecessary procedures, the authors evaluated the utility of immunodetection of p16 in liquid-based cytology specimens on cell blocks.

METHODS

Seventy-five liquid-based (SurePath; TriPath Imaging, Inc. Burlington, NC) cytology specimens were prepared for cell blocks. Three groups (G1, G2, and G3) of cases were included: G1 comprised 44 cases of ASC-H; G2, 14 cases of high-grade dysplasia; and G3, 17 negative/reactive cases. All cases in G1 were confirmed by cervical biopsy or Digene Hybrid Capture 2 (Digene, Gaithersburg, Md) human papilloma virus (HPV) testing. Immunodetection for p16 was performed on cell blocks.

RESULTS

In G1, 26 of 44 (59%) cases showed squamous dysplasia, with 14 high-grade squamous intraepithelial lesion (HSIL) cases. Twenty-two of 28 (79%) p16-positive cases were confirmed by surgical biopsy or HPV testing, with a diagnostic sensitivity of 85%, specificity of 67%, positive predictive value (PPV) of 79%, and negative predictive value (NPV) of 75%. Four cases with false-negative staining for p16 were identified. All 28 cases of HSIL (14 from G1 and 14 from G2) were positive for p16.

CONCLUSIONS

1) p16 is a sensitive marker to confirm the diagnosis of ASC-H on a cell block; 2) Multiple unstained slides with adequate cellularity can be obtained from each cell block; and 3) Additional markers can be used to further increase diagnostic sensitivity and specificity.

A comparison of the clinical utility of p16(INK4a) immunolocalization with the presence of human papillomavirus by hybrid capture 2 for the detection of cervical dysplasia/neoplasia

BACKGROUND

Evidence suggests that overexpression of p16(INK4a) protein indicates infection and genomic integration of high-risk human papillomavirus (HR HPV) and predicts progression to cervical high-grade squamous intraepithelial lesions (HSILs) and carcinoma. The authors compared the ability of p16(INK4a) and HR HPV detection by Hybrid Capture 2 (HC2) to detect the presence of significant cervical disease. METHODS.: Four hundred ThinPrep specimens (100 each in 4 categories: 100 specimens that were negative for intraepithelial lesions, 100 specimens of atypical squamous cells of undetermined significance [ASC-US], 100 specimens of low-grade squamous intraepithelial lesions [LSILs], and 100 specimens of HSILs) were analyzed. p16(INK4a) protein was immunolocalized using a specific monoclonal antibody, and the detection of HR HPV in all 400 specimens was determined using HC2.

RESULTS

p16(INK4a) was found to be positive in 78% of HSIL specimens, 42% of LSIL specimens, and 36% of ASC-US specimens; whereas HC2 was positive in 92% of HSIL specimens, 81% of LSIL specimens, and 45% of ASC-US specimens. In the HSIL category, the sensitivity, which was calculated using Grade 2 or greater cervical intraepithelial neoplasia as the endpoint, was 78% (50 of 66 specimens) for p16(INK4a) and 91% (60 of 66 specimens) for HC2. For LSIL, the sensitivity was 75% (3 of 4 specimens) for p16(INK4a) and 100% (4 of 4 specimens) for HC2. In the ASC-US category, the sensitivity was 89% (8 of 9 specimens) for p16(INK4a) and 100% (9 of 9 specimens) for HC2. Overall, the sensitivity for HSIL was 92% for HC2 and 78% for p16(INK4a). The specificity for HC2 was 8.3% for HSIL, 16.9% for LSIL, and 48.7% for ASC-US; whereas the specificity for p16(INK4a) was 25% in HSIL, 59.1% in LSIL, and 68.4% in ASC-US. The overall specificity was 25% for HC2 and 56% for p16(INK4a).

CONCLUSIONS

Although both p16(INK4a) and HC2 may aid in the clinical management of patients with clinically significant lesions, HC2 was found to have greater sensitivity, and p16(INK4a) greater specificity. The labeling of normal cells and bacteria may preclude the use of p16(INK4a) in automated screening or nonmorphologic assays.

Evaluation of a nuclear score for p16INK4a-stained cervical squamous cells in liquid-based cytology samples

BACKGROUND

The p16INK4a gene product is overexpressed strongly in abnormal cervical epithelia and may serve as a valuable biomarker to identify abnormal cells in cervical smears or liquid-based cytology samples.

METHODS

The authors performed p16INK4a immunocytochemistry to locate cells that expressed p16INK4a in liquid-based cytology samples and used a nuclear scoring system based on several morphologic criteria to interpret the degree of abnormality of these cells.

RESULTS

Among 108 samples that were scored as normal in Papanicolaou-stained, parallel slides, any p16INK4a-positive cells were observed in 13 samples (12%), but only 1 of 108 samples (1%) was scored abnormal after applying nuclear scoring criteria. In the group of 52 low-grade squamous intraepithelial lesion (LSIL) samples, 19 samples (37%) were positive for any p16INK4a reactivity, but only 5 of those samples (10%) were scored abnormal after applying the nuclear score. Among the 50 high-grade squamous intraepithelial lesion (HSIL) samples, 49 samples (98%) were positive for p16INK4a and were scored as abnormal. Comparison of the scoring results of independent observers revealed good reproducibility of the nuclear score.

CONCLUSIONS

The current results suggested that p16INK4a enables the location of potentially abnormal cells on liquid-based cytology samples. The nuclear score facilitated interpretation of the degree of abnormality of p16INK4a-stained cells. Thus, locating potentially abnormal cells by p16INK4a immunocytochemistry and their interpretation based on the nuclear score described here may help to identify patients with HSIL in cytologic screening programs and may represent a new approach for reducing the number of equivocal or misinterpreted cytologic specimens.

Immunocytochemical expression of p16INK4A and Ki-67 in cytologically negative and equivocal pap smears positive for oncogenic human papillomavirus

This study was designed to analyze the cross-sectional comparison of the p16 and Ki-67 immunocytochemical expression in negative and equivocal (atypical squamous cells of undetermined significance (ASC-US)) liquid-based cytology (LBC) samples testing positive for high-risk human papillomavirus (HPV) types with HC2 assay or polymerase-chain reaction (PCR). A series of 199 consecutive LBC specimens derived from the same number of women participating in the ongoing Latin American Screening Study at Leonor Mendes de Barros Hospital, Sao Paulo, were analyzed using immunocytochemistry for expression of p16 and Ki-67 in negative and equivocal LBC samples testing positive for high-risk HPV types with hybrid capture II test (HC2) or PCR. All patients with at least one test positive (cytology, PCR, and/or HC2) were followed each 6 months for 3 years. The follow-up procedure consisted of visual examination, colposcopic inspection, cytology, and HC2 assay. Among the negative cytologic samples, 101 were HPV-positive and 55 HPV-negative. Of the HPV-positive group, 59 of 101 cases (58.4%) were positive for both p16 and Ki67 immunostaining, and 17 of 101 (16.8%) were negative for both. The proportion of Ki-67-positivity increased almost in parallel with the increasing grade of p16-positivity (p = 0.0001 for linear trend). In the HPV-negative group, both markers were negative in 41 of 55 cases (74.5%), and no statistical relationship was observed between the two markers (Pearson, p = 0.595). HPV-positive ASC-US samples demonstrated a simultaneous positive immunoreaction for p16 and Ki67 in 11 of 16 cases (68.7%), whereas 3 (18.7%) were concurrently negative. The relationship between the two markers was of borderline significance (Pearson, p = 0.053), but no linear relationship was found between the graded p16 and Ki-67 expression (p = 0.065 for linear trend). In the HPV-negative ASC-US group, there was no statistical association between the graded p16 and Ki-67 positivity (Pearson, p = 0.281). After 36 months of follow-up of the ASC-US patients, 6 women still displayed ASC-US smear, of which 4 of 6 were HPV-positive and expressed both p16 and Ki-67 markers. Two of 43 ASC-US smears had high-grade squamous intraepithelial lesions diagnosed (4.6%), and 1 had low-grade squamous intraepithelial lesion (2.3%). All of those were positive for HPV, p16 and Ki-67. Patients with ASC-US diagnosis and positive high-risk HPV status and positive for p16 Ki67 should be carefully observed to exclude occurrence of a squamous intraepithelial lesion. The combination of these two markers can be a useful implement for management of women with equivocal cytology.

P-cadherin expression in glandular lesions of the uterine cervix detected by liquid-based cytology

OBJECTIVE

To study P-cadherin aberrant expression as a possible marker for cervical adenocarcinomas in cytological samples.

METHODS

We studied P-cadherin immunoexpression in liquid-based cervical cytology samples of biopsy-proven cervical lesions.

RESULTS

We found a statistically significant correlation between P-cadherin expression and a cytological diagnosis of malignancy, either glandular or squamous (P < 0.0001). Twenty-two of 33 malignant cases showed P-cadherin membrane staining. None of the 30 benign cases tested showed membrane staining, but three of them displayed an aberrant nuclear P-cadherin expression.

CONCLUSIONS

We concluded that P-cadherin can be used to discriminate between malignant and benign cervical cytological specimens, but not to discriminate glandular from squamous lesions.