Prediction of 'high-risk' cervical papillomavirus infection by biopsy morphology

Cervical Pre-cancers: Biopsy and Immunohistochemistry

The existence of precursor lesions for invasive cervical cancer has been recognized for more than 50 years. Our understanding of the pathobiology and behavior of cervical cancer precursors has evolved considerably over the past five decades. Furthermore, the terminology used to classify pre-invasive lesions of the cervix has frequently changed. The realization that human papillomavirus (HPV) infections constitute a morphologic continuum has prompted efforts to include them within a single classification system, specifically the squamous intraepithelial lesions (SILs) which have now been embraced by the surgical pathologists. The reduced number of specific pathological categories has made clinical decision-making more straightforward. The generic criteria for SIL have two important histological parameters: Alterations in the density of superficial epithelial cells and superficial squamous atypia. The flat condyloma or cervical intraepithelial neoplasia (CIN) I is generally associated with intermediate and high-risk HPV types as against the low-risk viruses that cause exophytic/papillary growth patterns of condylomas. The diagnosis of low-grade SIL (LSIL) (flat and exophytic condylomas) requires first excluding benign mimics of LSIL and second to confirm the characteristic cytologic atypia. For high-grade SILs (HSILs), the extent and degree of atypia generally exceed the limits of that described in flat or exophytic condylomas (LSILs). Less maturation, abnormal cell differentiation, loss of cell polarity, and increased mitotic index with abnormal mitotic figures occupying increasing thickness of the epithelium define a lesion as CIN II or CIN III. Atypical immature metaplasia associated with inflammation and atrophy is a challenge in cervical biopsy interpretation. Careful attention to the growth pattern of the epithelium, the distribution of the atypia, nuclear spacing, and the degree of anisokaryosis and the presence of enlarged hyperchromatic nuclei help in differentiating a non-neoplastic from a neoplastic process. This chapter describes in depth the diagnostic difficulties in the interpretation of cervical biopsies. It also provides useful criteria in distinguishing benign mimics from true precancerous lesions and the role of biomarkers such as the p16ink4 and Ki-67 in the differential diagnosis of precursor lesions and the reactive and metaplastic epithelium.

Epstein-Barr virus, but not human cytomegalovirus, is associated with a high-grade human papillomavirus-associated cervical lesions among women in North Carolina

STATEMENT OF THE PROBLEM

Human papillomavirus (HPV) infection is known to contribute to cervical carcinogenesis, yet other cofactors that may contribute to oncogenesis are poorly understood. Herein, we examine whether the Epstein-Barr virus (EBV) and human cytomegalovirus (CMV), two oncomodulatory viruses, are associated with HPV-mediated cervical neoplastic progression.

METHODS

Sixty patient cervical brush samples from a study of North Carolina women were obtained. HPV RNA positivity was determined by Aptima testing (Hologic Corporation, Marlborough, MA). The level of viral transcripts for EBV and CMV was quantified (reverse transcription polymerase chain reaction analysis), and the coinfection status with HPV was then compared with the patient's cervical cytology grade.

RESULTS

Over one-third (38.3%) of the study population was CMV positive, whereas 43.3% was EBV positive. When sample data were stratified by the cytology grade, 36.5% (19/52) of normal patients, 75% (3/4) of low-grade squamous intraepithelial lesions (LSIL), and 100% (4/4) of patients with high-grade SIL (HSIL) were EBV positive. Conversely, 35.2% (18/52) of normal patients, 25% (1/4) of patients with LSIL, and 50% (2/4) of patients with HSIL were CMV positive. When examining only HPV positive-associated HSIL, 100% (4/4) were positive for both HPV and EBV detection. This suggests that co-viral detection with HPV and EBV is associated with more advanced HSIL cervical lesions, while CMV displayed no clear association with a higher grade of cervical cytology.

CONCLUSIONS

Co-viral detection with EBV may increase the oncogenicity and/or serve as a viral marker of progression to HPV-associated high-grade cervical dysplasia.

Replication and assembly of human papillomaviruses

Human papillomaviruses (HPVs) are small dsDNA tumor viruses, which are the etiologic agents of most cervical cancers and are associated with a growing percentage of oropharyngeal cancers. The HPV capsid is non-enveloped, having a T=7 icosahedral symmetry formed via the interaction among 72 pentamers of the major capsid protein, L1. The minor capsid protein L2 associates with L1 pentamers, although it is not known if each L1 pentamer contains a single L2 protein. The HPV life cycle strictly adheres to the host cell differentiation program, and as such, native HPV virions are only produced in vivo or in organotypic "raft" culture. Research producing synthetic papillomavirus particles--such as virus-like particles (VLPs), papillomavirus-based gene transfer vectors, known as pseudovirions (PsV), and papillomavirus genome-containing quasivirions (QV)--has bypassed the need for stratifying and differentiating host tissue in viral assembly and has allowed for the rapid analysis of HPV infectivity pathways, transmission, immunogenicity, and viral structure.

[Natural history of precursor lesions of cervical cancer]

Precursor lesions of invasive cancer of uterine cervix begin at the squamocolumnar junction. On this zone in permanent transformation, human papillomavirus (HPV) gives condylomatous lesions, pure or associated with neoplasic transformation of the epithelium. For 50 years, various histological classifications have been proposed. First, four groups have been designed: light, moderate, severe dysplasia and in situ carcinoma. Secondly, Richart proposed the cervix intraepithelial neoplasia classification (CIN) with three grades (1 to 3) according to their severity. Progression from CIN 1 to CIN 3 and invasive carcinoma is admitted and is consistent with the concept of lesional continuum. However, because of the elevated rate of spontaneous regression of CIN 1, it is probably a lesion of very low potential aggressivity and its role as a precursor is uncertain. Now two groups of different evolutivity are currently considered: low grade and high grade lesions. The last one's, at the opposite of the first, are monoclonal, have major epithelial abnormalities with sometimes abnormal mitoses and are frequently aneuploid. Aggressivity depends on the persistence of HR HPV more than on progressive morphologic transformation. By integrating in-host genoma, it induces modifications on cellular cycle proteins. Revelation by immunohistochemistry brings help to diagnosis of high grade lesions when traditional morphology is ambiguous.

Expression of Ki-67 and squamous intraepithelial lesions are related with HPV in endocervical adenocarcinoma

To estimate the association between human papillomavirus (HPV) status and the expression of p53, Ki-67 and bcl-2 in cases of endocervical adenocarcinoma, and the relation with squamous intraepithelial lesions (SIL) and age, 229 cases were selected, treated between 1995 and 2003 in the Hospital Nossa Senhora da Conceiçao. All samples were evaluated by polymerase chain reaction to determine HPV status. Immunohistochemical technique was used to investigate the expression of p53, Ki-67 and bcl-2. The joint occurrence of endocervical adenocarcinoma and SIL were estimated too. In the 229 evaluated cases, 182 cases (79.48%) were associated with the presence of the HPV. The most common types were HPV18 (93 cases - 51.09%) and HPV16 (62 cases - 34.06%). Expression of Ki-67 (p=0.009) and the presence of SIL (p=0.018) were associated to HPV infection. Expression of p53 (p=0.647) and bcl-2 (p=0.671) were not related to HPV status. The mean age of the patients was 53.2 years, without clear correlation between age group and HPV (p=0.095). The presence of HPV, especially type 18 in endocervical adenocarcinoma suggests that this agent can be an important cofactor in the development and progression of glandular neoplasms of the uterine cervix. The joint occurrence of endocervical adenocarcinoma and SIL may support this hypothesis. HPV may promote an increased proliferation index in endocervical adenocarcinoma, shown by the expression of Ki-67.

Immunohistochemical analysis of gynecologic tumors

Ancillary techniques such as immunohistochemistry (IHC) enable the surgical pathologist to extract additional information from fixed, deparaffinized tissue specimens and to provide data critical to optimal clinical management of the patient. In this review of applications of IHC to the analysis of gynecologic malignancies, the usefulness of immunohistochemical analysis of neoplasms of the cervix, endometrium, and ovary is summarized. In the uterine cervix, dysplasia is associated with qualitative and quantitative alterations in the expression of the Ki-67 antigen expression, as well as an ability to detect human papillomavirus. Endometrial endometrioid adenocarcinomas display a highly characteristic immunophenotype, with coexpression of cytokeratin and vimentin and demonstration of foci of high molecular weight cytokeratin expression; in addition, IHC analysis of estrogen and progesterone receptor and p53 expression can provide important prognostic information about this tumor. Stromal tumors of the endometrium may display a partial smooth muscle immunophenotype, but novel markers such as CD10 provide new tools for the identification of these tumors. The immunophenotypes of the normal ovarian surface epithelium (OSE) and corresponding tumors display significant overlap with, but important distinctions from, mesothelium, and important new markers such as the Wilms tumor gene product can prove useful in the identification of carcinomas of the OSE. Important prognostic markers for carcinomas of the OSE include the HER-2/neu gene product and p53, alterations of which can both be assessed by IHC techniques. Finally, the recent availability of markers of ovarian stroma, including Melan-A and inhibin-alpha, has provided a means for the positive identification of ovarian stromal tumors, which can manifest protean histological appearances.

Disparities in mean age and histopathologic grade between human papillomavirus type-specific early cervical neoplasms

Noninvasive squamous and glandular precursor lesions associated with human papillomavirus (HPV) types 16 and 18 have been reported to vary in morphology. HPV 16 is associated predominantly with high-grade squamous intraepithelial lesions (HSIL; cervical intraepithelial neoplasia (CIN 2 and 3), and HPV 18 is associated with low-grade squamous intraepithelial lesions (condyloma/CIN 1) and CIN 3/adenocarcinoma in situ (ACIS). This study explored the relationship of morphologic growth pattern in these precursor groups with age of presentation. One hundred fourteen CIN lesions (including those with ACIS), associated with HPV 16 or 18, were subdivided into well-differentiated low- and high-grade SIL (CIN 1 and 2, respectively), poorly differentiated HSIL (CIN 3) with or without ACIS. HPV was detected by polymerase chain reaction (PCR) amplification with L1 consensus or type-specific E7 primers and typed by restriction fragment length polymorphism (RFLP) analysis. Age of the patient was obtained from the pathology report. Mean age for each group was as follows: Low-risk HPVs, 25 years; HPV 18 CIN 1-2, 21.6 yrs; HPV 18 CIN 3/ACIS, 35.2 yrs; HPV 16 CIN 1,2, 25.9 yrs; and HPV 16 CIN 3, 29.8 yrs. There were significant differences in mean ages between HPV 18 CIN 1 and 2 and HPV 16 CIN 1 to 2 (P = .04), HPV 16 CIN 1-2 and CIN 3 (P = .01) and HPV 18 CIN 1 to 2 and HPV 18 CIN 3/ACIS (P = .00001). None of the cases of HPV 18-associated CIN3/ACIS was associated with a CINI lesion. The disparity in mean ages between well and poorly differentiated HPV 16/18 related that precursor lesions could reflect factors such as morphologic progression with increasing age, different rates of lesion persistence, depending on grade, or efficiency of detection between the two groups. The marked difference in mean age between HPV 18-associated CIN 1-2 and CIN 3/ACIS, combined with their lack of coexistence in the same cervix, raises alternate possibilities that specific viral or host factors may determine the morphological phenotype associated with some HPV 18 infections. In the latter, the possibility that age independently confers an increased risk for higher-grade lesions should be considered.

Characterization and functional analysis of the expression of vascular adhesion molecules in human papillomavirus-related disease of the cervix

BACKGROUND

Cervical intraepithelial neoplasia (CIN) is associated with changes in local immune cell populations, although the role of vascular adhesion molecules in mediating such changes by controlling the traffic of mononuclear cells to the cervix has not been investigated previously.

METHODS

The authors used immunohistochemistry to examine the expression of three vascular adhesion molecules--ICAM-1, VCAM-1 and E-selectin--in the normal cervix and in biopsies of CIN Grade 1 (CIN-1) (low grade squamous intraepithelial lesions [LG-SIL]) and CIN-2/3 (high grade squamous intraepithelial lesions[HG-SIL]). In addition, the authors examined the functional role of these molecules by adapting the frozen section adhesion assay of Stamper and Woodruff to investigate in vitro the molecular basis of the interaction between cervical endothelial cells and activated T-lymphocytes.

RESULTS

Whereas there was no difference in adhesion molecule expression between normal cervix and CIN-1 (LG-SIL), all three molecules investigated were significantly up-regulated in CIN-2/3 (HG-SIL), an observation that correlated with an enhanced ability of stromal endothelial cells in CIN-2/3 (HG-SIL) biopsies to bind activated peripheral blood lymphocytes in vitro. Monoclonal antibodies blocking ICAM-1 function were able to reduce such adhesion significantly in three of three experiments, and antibodies blocking VCAM-1 produced a significant reduction in one of three experiments. No inhibition was seen with antibodies against E-selectin.

CONCLUSIONS

The enhanced expression of vascular adhesion molecules in CIN-2/3 (HG-SIL) appears to be functionally important in enabling the local recruitment of immunocompetent cells and supports the notion of a local antineoplastic immune response in high grade cervical intraepithelial lesions.

Human papillomavirus testing in the clinical laboratory. Part I: squamous lesions of the cervix

The aim of this study was twofold: (1) to evaluate the contribution of viral (HPV) testing for improving the sensitivity of cervical cytology and (2) to correlate HPV types with the histology of the detected cervical cancer precursors, particularly the low-grade, CIN I variant. We used the dot blot hybridization technique (ViraPap) and polymerase chain reaction (PCR) in 63 women referred to our colposcopy clinic for evaluation of an abnormal Pap test. Histopathologic samples obtained by multiple colposcope-directed punch biopsies were used for a diagnostic gold standard. Among the 53 women with histologically proven CIN, precolposcopy cytology was positive in 38 (72%) compared to 53% and 60% HPV positivity by ViraPap and PCR, respectively (p less than 0.01). When the yields of ViraPap/PCR and cytology were combined, however, the detection rate of CIN was 91%, a significant improvement over cytology alone (p less than 0.02). HPV DNA was found either by ViraPap or PCR in 45 of 63 (71%) biopsy specimens, and 37 of 38 (97%) HPV-positive CIN, including the low-grade CIN I variant, contained oncogenic HPV types. HPV type 16 was present in 22 of 38 (58%) CIN lesions and mixed with HPV 6/11, 18, or the 30s group in 6 of 38 (16%) of the cases. HPV 6/11 alone was found only in 1 case of CIN I (2.7%). HPV testing by molecular technology increases the sensitivity of cytology.(ABSTRACT TRUNCATED AT 250 WORDS)

A binary (Bethesda) system for classifying cervical cancer precursors: criteria, reproducibility, and viral correlates

This study of cervical squamous precursors addressed the consistency with which pathologists could agree on diagnosis using a Bethesda system and the degree to which the classification system discriminated "high-risk" human papillomavirus (HPV) types. Four pathologists independently assessed biopsies of 75 squamous lesions; all contained HPV DNA amplified from archival fixed tissue with polymerase chain reaction (PCR) and typed by restriction digestion of the PCR product. Lesions were categorized as low or high grade using published criteria. In independently performed histologic evaluations a majority (three or more) of observers agreed on the classification of 63 of the 75 cases (84%) with good to very good interobserver (kappa values, 0.43 to 0.63), and fair to excellent intraobserver (kappa values, 0.32 to 0.83) agreement. A majority of the observers classified as high grade 15 of 17 (88%) HPV 16-positive lesions (P < .002), but only 15 of 21 (71%) lesions associated with other high-risk HPV types 18, 31, 35, and 39 (P = .089). Concurrence among observers also varied with HPV type; majority agreement between three or more observers was present for 100% and 94%, respectively, for lesions associated with HPV 6/11 and HPV 16 versus 82% and 76% for lesions associated with HPV 18/31/35/39 and other HPV types. A binary system for grading cervical precursor lesions was applied with good reproducibility among pathologists, and segregated as high-grade virtually all lesions associated with the prototype high-risk HPV (HPV 16). Conversely, other presumed high-risk HPV types, particularly type HPV 18, were not distinguished by this grading scheme and were segregated frequently with low-grade lesions. This finding suggests that variables other than HPV type alone will influence lesion grade. Resolution of these variables will determine whether lesion grade is a more potent biologic parameter than HPV type.

In situ hybridization for human papillomavirus as a method of predicting the evolution of cervical intraepithelial neoplasia

Twenty-four women with cervical condylomata which were immunohistochemically positive for human papillomavirus (PV-Ag) (15 with CIN 1 and 9 with CIN 2) were followed for a period of 2-65 months. Fifty-seven biopsies were studied by the in situ hybridization (ISH) procedure for the detection of HPV 6/11 and 16/18 DNA. ISH positivity was found in 13/24 cases (54.2%); HPV 16/18 was evident in 7/9 CIN 2 (77.8%) as against 3/15 CIN 1 (20%) (P = 0.017) and in 8/13 cases with koilocytosis affecting up to 2/3 of the epithelial thickness (61.5%) as against 2/11 cases with koilocytosis affecting more than 2/3 of the epithelial layer (18.2%) (P = 0.03). Progression to CIN 3 occurred in 4 cases (2 CIN 1 and 2 CIN 2), the degree of dysplasia remained static in 5 cases (1 CIN 1 and 4 CIN 2) and regression occurred in 15 cases (9 CIN 1 and 6 CIN 2). The immunoperoxidase (IP) positive staining for PV-Ag persisted in 5/24 cases and disappeared in 19/24; 6/13 ISH positive cases maintained ISH positive and 7/13 became negative. The progression of dysplasia was significantly related to disappearance of the IP positivity (P less than 0.0001), to the ISH positivity (P = 0.05), to the persistence of ISH positivity (P = 0.008) and to HPV 16/18 positivity (P = 0.01). We believe that ISH positivity for HPV 16/18 in CIN 1 or 2 with low degrees of koilocytosis and conversion from PV-Ag positive to negative indicate a high risk of progression to CIN 3.

Human papillomaviruses associated with cervical intraepithelial neoplasia. Great diversity and distinct distribution in low- and high-grade lesions

All together, 30 genital human papillomavirus (HPV) types have been characterized so far. To evaluate the importance of HPV diversity in associated cervical diseases, we analyzed 188 biopsy specimens obtained from patients with a recent diagnosis of cervical HPV infection or intraepithelial neoplasia (CIN). Of these 188 specimens, 116 were classified as low-grade CIN (48 cases), high-grade CIN (53 cases), condylomata acuminata (10 cases), flat condylomas (five cases). Seventy-two specimens were considered nondiagnostic. Using probes specific for 18 genital HPV types, HPV DNA sequences were detected by Southern blot hybridization in 100 lesions and 21 nondiagnostic specimens. When further analyzed by the polymerase chain reaction, eight HPV-negative biopsy specimens, four CIN, and four nondiagnostic specimens were positive. Of the 129 positive biopsy specimens, 92 contained at least one of 18 known HPV types and 37 HPV that have not yet been identified. Nine specimens had more than one type. Thirteen HPV types were identified in CIN. The detection rate of HPV 16 increased from 21% in low-grade CIN to 57% in high-grade CIN. HPV 18 was detected in only 3% of CIN; HPV 31, 33, and 35 were found in 8%. HPV 30, 39, 45, 51, 52, 56, 58, and 61 were detected in 44% of low-grade CIN but in only 8% of high-grade CIN. Unidentified HPV were detected in about 25% of low-grade and high-grade CIN. Fifty-seven CIN positive for at least one HPV type were further analyzed by in situ hybridization. Thirty-five (65%) biopsy specimens were positive, including 21 of 24 low-grade CIN and 14 of 33 high-grade CIN. Ten of the 13 previously identified HPV types were detected. Thus, CIN represents an heterogeneous disease from a virologic viewpoint. This fact could explain their variable clinical evolution.

Screening for high- and low-risk human papillomavirus types in single routine cervical smears by non-isotopic in situ hybridization

Routine cervical smears (n = 262) from a Sexually Transmitted Diseases clinic were screened by non-isotopic in situ hybridization (NISH) stratifying human papillomavirus (HPV) infections into HPV6/11 (low risk) and HPV16/18/33 (high risk) categories. Of 188 patients with cytologically normal smears, HPV sequences were demonstrated in 41%. Of the 128 cases analysed by dual NISH, 16% contained low risk, 20% high risk and 5% both groups. In patients with cytological evidence of wart virus infection (WVI) only, 54% (n = 50) contained high-risk and 22% low-risk HPV types. The comparable incidences in CIN1/2 plus WVI (n = 24) were not significantly different: 54% and 17%, respectively. Cytological criteria underestimate the prevalence of HPV infection in patients with cytologically normal smears. This represents either 'occult' or 'latent' infection. The identical prevalence of HPVB16/18/33 in WVI only, and CIN1/2 plus WVI, suggests that the cytopathic effect induced by these HPVs may represent one end of a spectrum of morphological change which progresses to cervical intraepithelial neoplasia (CIN).

Analysis of transforming gene regions of human papillomavirus type 16 in normal cervical smears

Exfoliated cells from the uterine cervix of 102 Hungarian women with no cytological abnormality were screened using the polymerase chain reaction (PCR) for human papillomavirus (HPV) type 16 infection. Twenty-nine patients with histologically confirmed cervical intraepithelial neoplasia (CIN) served as reference cases. PCR was performed with 2 different HPV 16 specific oligonucleotide primer pairs flanking a 300 and a 200 base-pair fragment from the early 6 (E6) and early 7 (E7) genes, position 215-514 and 605-805. The specimens exhibited the same proportions of type 16 sequences specific for the tested regions. 8.8% (9/102) of normal samples showed amplification for HPV type 16 E6 and E7 regions, while 48.3% (14/29) of CIN biopsies were positive for the same gene sequences.

Pathobiology of papillomavirus-related cervical diseases: prospects for immunodiagnosis

In recent years, the relationship between human papillomaviruses (HPV) and genital neoplasia has been explored intensively, and a molecular basis for the role of HPV in the genesis of these diseases has been convincingly demonstrated. These findings have provided justification for efforts to apply this molecular information to the early detection and possible prevention of HPV-related neoplasia. The technology of detecting viral nucleic acids in genital fluids brought with it initial hopes that it would serve to identify women at risk for having or developing precancers or cancers of the cervix. Subsequent studies, however, have demonstrated limitations of the technology for predicting future disease. Recently, molecular immunology has complemented these prior efforts, with the intent to identify serological indices of exposure to HPV and perhaps delineate individuals at risk. The molecular basis for this approach, its limitations, and future prospects for immunodiagnosis are the subject of this review.

In situ human papillomavirus (HPV) genotyping of cervical intraepithelial neoplasia in South African and British patients: evidence for putative HPV integration in vivo

In South Africa asymptomatic wart virus infection diagnosed by morphological criteria occurs in 16-20% of all ethnic groups; the incidence in black women is 66%. To identify human papillomavirus (HPV) types the prevalence of HPV in cervical intraepithelial neoplasia (CIN) in South African women (n = 72) with age matched British women (n = 73) was compared by non-isotopic in situ hybridisation (NISH) using digoxigenin labelled probes for HPV 6, 11, 16, 18, 31, 33 and 35 on archival biopsy specimens. A higher proportion of British biopsy specimens (68%) contained HPV than those from South Africa (50%) in CIN 2 and 3; this difference was due to HPV 16. Thirty six per cent of the positive biopsy specimens from South African women also contained HPV 33/35 compared with 16% in the United Kingdom. There was no difference in HPV detection with age in either group. These data indicate that HPV types vary geographically, with "minor" HPV types being more common in South Africa. Three qualitatively distinct NISH signals were observed; a diffuse (type 1) signal in superficial cells, mainly koilocytes; a punctate signal (type 2) in basal/"undifferentiated" cells in CIN 3; and combined type 1 and 2 signals in CIN with wart virus infection (type 3). The punctate signal may represent HPV integration.

Penile human papillomavirus carriage among men attending Swedish STD clinics

Using the polymerase chain reaction (PCR) technique, we found that up to 84% of 228 men consecutively attending two Swedish STD clinics harboured human papillomavirus (HPV) types 6 or 16. Mean age of the patients was 28 years (range 17-58); 70% were between 17 and 30 years old. Among men without a previous history of, or contact with, condylomata the frequency of HPV 6 detection was 76% using the PCR/dot blot (DB) analysis and 43% with the PCR/agarose gel (AG) technique. The corresponding figures for HPV 16 were 46% and 13%, respectively. These figures were comparable to those found in men with existing condylomata infection or sexual exposure to a partner with condylomata. Although the test group represents a selected high-risk population for STD including HPV, our results indicate that a high frequency of occult HPV carriage exists among sexually-active males. The significance of these findings is discussed.

Current problems in the pathology of intra-epithelial lesions of the uterine cervix

Problems in the interpretation and diagnosis of intraepithelial lesions of the uterine cervix include interobserver differences in respect of grading, uncertainty as to the significance of human papillomavirus infection and debate about the current terminology. The role of human papillomaviruses in cervical intra-epithelial neoplasia (CIN) remains unclear and the specific type of virus present does not correlate closely with the behaviour of these lesions. There are defects in the current terminology and in proposed new terminology for CIN; it is suggested that the term 'borderline CIN' should be introduced in cases where there is uncertainty as to whether or not CIN 1 is superimposed on a flat condyloma.