Growing up with juvenile vulvar lichen sclerosus, the experiences and care needs of adult women with lichen sclerosus since childhood: a qualitative exploration.

BACKGROUND: Vulvar Lichen Sclerosus (VLS) is a chronic remitting condition affecting the genital skin of females of all ages. Although qualitative studies have been conducted focusing on women with VLS in mid-life or older, less is known about the experiences of individuals with VLS from childhood or adolescence onward. OBJECTIVE: To gain understanding of the experiences of women with a history of juvenile VLS (JVLS) regarding the impact of the disease on their personal lives, and their experiences and needs regarding care and guidance. METHODS: A qualitative study was conducted consisting of 27 in-depth face-to-face interviews with adult women with a histologically confirmed history of JVLS, striving for maximum variation and saturation. Interviews were audio-taped and transcribed verbatim. A thorough thematic content analysis was performed. RESULTS: Three main themes were identified. I. Varying impact of living with JVLS: Women experienced diverse emotional and physical impact, from shame and denial to complete acceptance, from restrictions in daily functioning to no limitations. They felt hindered by their own lack of knowledge about JVLS, and generally expressed a positive influence of sharing their experiences with people close to them. II. Finding one's way in care and guidance: While navigating care and guidance, women often felt hindered by knowledge gaps among health care professionals (HCPs), lack of continuity in care and guidance, lack of life-stage adjusted and future-oriented information provision, inadequate guidance around life events, and insufficient monitoring of determinants of therapy adherence. III. Need for patient-tailored care: Patients stressed the need for age-appropriate and life-phase adjusted information, guidance around life-events and compassionate contact with knowledgeable HCPs, aware of the determinants of therapy adherence and influencing factors. CONCLUSIONS: Age-appropriate life-phase adjusted individually tailored care for women diagnosed with VLS in childhood or adolescence is needed. Care and guidance from childhood onward should encompass a standard of care adapted to the individual as needs change over time. This involves taking interpersonal differences into account, including differences in support network and coping strategies. These findings demonstrate the need for improving awareness and knowledge about (J)VLS among HCPs, especially primary care providers, and among the general public.

Outcome Measures in Adult Vulvar Lichen Sclerosus: A Case Series of Women Diagnosed as Juveniles.

OBJECTIVES: Studies on the consequences of juvenile vulvar lichen sclerosus (JVLS) in adulthood are limited. A number of measuring tools are available for analyzing adult vulvar lichen sclerosus (VLS), but these have not been applied in studies on JVLS. The aim is to study physical findings, quality of life, sexual well-being, and self-image in adult women with a history of juvenile VLS. MATERIALS AND METHODS: Adult women with a biopsy proven history of JVLS were recruited to be examined and surveyed using available standardized measurement tools. This took place in an outpatient setting by physicians who were not involved in the treatment of participants. RESULTS: Twenty-seven women (median age 29 years) with a history of JVLS and median time since biopsy of 19.5 years were recruited. Of these women, 59% currently had symptoms, 63% had signs of active disease, and 85% had moderate to severe architectural changes. Despite these residual signs, vulvar specific-quality of life and vulvar self-image scored favorably while generic health-related quality of life was somewhat effected. CONCLUSIONS: JVLS has consequences in adulthood involving physical findings and vulvar quality of life. The use of standardized outcome measures for clinical practice and research purposes facilitates a better understanding of the sequelae to JVLS.

Outcome Measures in Adult Vulvar Lichen Sclerosus: A Systematic Review.

OBJECTIVES: Core outcome domains (CODs) for treatment of adult vulvar lichen sclerosus (VLS) have recently been established through a Delphi study. A number of measuring tools are available for evaluating VLS. The aim of this study is to identify available standardized measurement tools for the major CODs for VLS that have recently been defined, namely, physical findings and quality of life (QoL) specific to VLS. MATERIALS AND METHODS: A systematic search through September 8, 2023, for measuring tools applicable to VLS regarding physical findings and QoL including sexual function or sexual well-being and self-image was performed. RESULTS: Thirty-five studies were included in the systematic review describing 26 tools covering the following 6 outcome domains: QoL-general health, QoL-lichen sclerosus specific, symptoms, clinical signs, emotional impact, and sexual functioning. CONCLUSIONS: In current research, there is no uniformity in use of measurement tools for evaluating VLS. The established CODs to evaluate treatment of VLS are applicable for evaluating disease course as well. A comprehensive study to reach consensus regarding measurement of physical findings, QoL-lichen sclerosus specific, sexuality, and self-image taking the predetermined CODs and other factors such as age into account is needed.

Long-term consequences of juvenile vulvar lichen sclerosus: A cohort study of adults with a histologically confirmed diagnosis in childhood or adolescence.

INTRODUCTION: Vulvar lichen sclerosus (VLS) occurs in at least one in 900 girls. There is limited knowledge as to what extent the disease persists in adulthood and what the repercussions in adulthood may be. The aim of this study is to evaluate the long-term consequences of VLS diagnosed in childhood or adolescence. MATERIAL AND METHODS: The population of females histologically diagnosed with VLS in childhood or adolescence in the Netherlands between 1991 and 2015 was identified through the national pathology database. Histological specimens were retrieved and re-evaluated. Potential participants for whom the diagnosis was reconfirmed and who are now adults, were then traced and surveyed. Descriptive statistics were calculated and compared with the literature. Main outcome measures are the demographics of the cohort, their scores on standardized quality of life (QoL) and sexuality questionnaires and answers to additional questions regarding patients' experience with the disease. The questionnaires used were the Dermatology Life Quality Index (DLQI), the Skindex-29, the Female Sexual Function Index (FSFI) and the Female Sexual Distress Scale-Revised (FSDS-R). Secondary outcome measures include obstetric history and histological features found in the original tissue specimens. RESULTS: A total of 81 women participated, median age 29.0 years, median follow-up from childhood diagnosis 19.5 years. Both QoL and sexuality were somewhat affected in 51.9% of cases. Less than half (45%) reported having regular check-ups. Forty-five (56%) reported symptoms within the past year; of those with symptoms, 14 (31%) were not under surveillance. Cesarean section rate (14.5%) was comparable to the general population, and there were more high-grade obstetric anal sphincter injuries with vaginal deliveries than expected. Sixteen respondents (20%) were not aware of the childhood diagnosis prior to this study. CONCLUSIONS: Symptoms due to VLS are reported by most adults diagnosed as juveniles. QoL and sexuality are affected and correlate to recent symptoms. VLS as a juvenile does not preclude a vaginal delivery. Women diagnosed with VLS in childhood or adolescence are often lost to follow-up.

The long-term clinical consequences of juvenile vulvar lichen sclerosus: A systematic review.

BACKGROUND: Vulvar lichen sclerosus (VLS) occurring in children and adolescents may have repercussions throughout life. OBJECTIVE: We sought to assess the evidence available on the long-term consequences of juvenile VLS. METHODS: Multiple databases were searched for studies containing long-term follow-up information on children or adolescents up to age 18 years with VLS. Articles were classified by level of evidence and the specific aspects of VLS studied. RESULTS: In all, 37 studies met the inclusion criteria, giving information on the long-term consequences of VLS, of which 13 were cohort studies and 24 were case reports or series. These publications show that signs and symptoms persist after puberty and beyond, scarring and permanent architectural changes occur, treatment is effective with regard to symptoms, and long-term quality of life is affected. Findings suggest a possible relationship with risk of malignancy. The included publications had low-level evidence. LIMITATIONS: Meta-analysis was not possible because the studies had different focuses. Very few patients were followed into adulthood. CONCLUSIONS: There is low-level evidence suggesting long-term repercussions of juvenile VLS. Studies following children and adolescents with VLS into adulthood are needed to better understand the course of this disease and its repercussions on adult vulvar health.

A Scoping Review and Population Study Regarding Prevalence and Histopathology of Juvenile Vulvar Melanocytic Lesions. A Recommendation.

Cases of vulvar melanocytic lesions in juveniles are rarely reported. We analyze the evidence regarding vulvar melanocytic lesions in juveniles with or without vulvar lichen sclerosus to help decision making by clinicians and pathologists. A scoping review on vulvar melanocytic lesions with or without vulvar lichen sclerosus, including malignant vulvar melanomas, in females up to age 18 years was performed. In addition, the histopathology records of the cohort of all such lesions in The Netherlands from 1991 through 2020 were investigated, and a structured analysis of tissue samples of the subset of cases with lichen sclerosus was performed. The literature study performed confirms that vulvar melanomas in juveniles are extremely rare and that published case reports are often disputed. In The Netherlands, there are no cases of malignant vulvar melanomas up to age 18 years recorded from 1991 through 2020. Atypical histopathological features are often found in biopsies of vulvar nevi in juveniles, especially with concomitant lichen sclerosus, confirming earlier case studies in the literature. We conclude that even with atypical findings, vulvar melanocytic lesions in juveniles have a benign course. To avoid unnecessary and possibly mutilating procedures, we advise referral to an expert center and adaption of existing guidelines for vulvar melanocytic lesions in juveniles.

Experiences and preferences towards collecting a urine and cervicovaginal self-sample among women attending a colposcopy clinic.

The effectiveness of cervical cancer screening is hampered by low attendance rates. The collection of a urine sample is hypothesized to engage non-attenders in cervical cancer screening. The aim of this prospective cohort study was to evaluate experiences of women on urine collection and cervicovaginal self-sampling in a home-based setting and preferences for future cervical cancer screening. This study included 140 women, with a median age of 40 years, who were planned for a large loop excision of the transformation zone (LLETZ) procedure. All women collected a urine sample using conventional urine cups and a cervicovaginal self-sample prior to the LLETZ in a home-based setting. Following sample collection, women filled in a questionnaire. Results showed that the instructions of urine collection and cervicovaginal self-sampling were considered clear (95%, 95%CI: 88-98; 92%, 95%CI: 83-96, respectively). Women considered urine collection compared to cervicovaginal self-sampling to be more acceptable (p < 0.001), and to provide more reliable results (p < 0.001). The three highest reported preferred sampling methods for future cervical cancer screening were: urine collection (n = 39, 28%, 95%CI: 19-39), clinician-taken cervical scrape (n = 32, 23%, 95%CI: 15-34), and equal preference for urine collection, clinician-taken cervical scrape and cervicovaginal self-sampling (n = 30, 21%, 95%CI: 14-32). In conclusion, urine collection and cervicovaginal self-sampling are acceptable sampling methods, considered easy to collect in a home-based setting, and moreover, considered trustworthy. Although these results are promising, more research is required to determine if urine collection also lowers the barrier for non-attendees and, thereby, increases the attendance rates of cervical cancer screening.

HPV and DNA Methylation Testing in Urine for Cervical Intraepithelial Neoplasia and Cervical Cancer Detection.

PURPOSE: Biomarker detection in urine offers a potential solution to increase effectiveness of cervical cancer screening programs by attracting nonresponders. In this prospective study, the presence of high-risk human papillomavirus (hrHPV) DNA and the performance of DNA methylation analysis was determined for the detection of cervical cancer and high-grade cervical intraepithelial neoplasia (CIN2/3) in urine, and compared with paired cervicovaginal self-samples and clinician-taken cervical scrapes. EXPERIMENTAL DESIGN: A total of 587 samples were included from 113 women with cervical cancer, 92 women with CIN2/3, and 64 controls. Samples were tested for hrHPV DNA and five methylation markers. Univariate and multivariate logistic regression and leave-one-out cross-validation were used to determine the methylation marker performance for CIN3 and cervical cancer (CIN3+) detection in urine. Agreement between samples was determined using Cohen kappa statistics and the Spearman correlation coefficients. RESULTS: HrHPV presence was high in all sample types, 79% to 92%. Methylation levels of all markers in urine significantly increased with increasing severity of disease. The optimal marker panel (ASCL1/LHX8) resulted in an AUC of 0.84 for CIN3+ detection in urine, corresponding to an 86% sensitivity at a 70% predefined specificity. At this threshold 96% (109/113) of cervical cancers, 68% (46/64) of CIN3, and 58% (14/24) of CIN2 were detected. Between paired samples, a strong agreement for HPV16/18 genotyping and a fair to strong correlation for methylation was found. CONCLUSIONS: HrHPV DNA and DNA methylation testing in urine offers a promising solution to detect cervical cancer and CIN2/3 lesions, especially for women currently unreached by conventional screening methods.

Relationship of human papillomavirus with seborrheic keratosis of the female genital tract - a case-series and literature review.

Seborrheic keratoses (SKs) are benign lesions of uncertain etiology, which can develop in both genital and extra-genital locations. For genital SKs, there has been conjecture about the pathogenic role of human papillomavirus (HPV), in view of the frequent association of this virus with genital lesions. In light of the potential consequences on patient management, we investigated the relationship between HPV and SKs of the female genital tract (FGT). For this, we evaluated the current evidence on this relationship by performing an in-depth review of the literature. Furthermore, to add to the evidence on this association, we investigated the presence of HPV in a series of vulvar SKs (n=15), using a novel multimodal approach. This involved whole tissue section-polymerase chain reaction (WTS-PCR) using SPF10-DEIA-LipA25 for HPV detection and genotyping. In addition, immunohistochemistry (IHC) was performed with cellular biomarkers p16 and MIB-1, and viral biomarker E4, to augment HPV-testing. Finally, laser-capture microdissection-PCR (LCM-PCR) was performed to locate HPV to specific lesional cells, and to rule out incidental detection of resident HPV with WTS-PCR. Our findings from the literature review, as well as, the case-series are presented.

A patient with lichen sclerosus, Langerhans cell histiocytosis, and invasive squamous cell carcinoma of the vulva.

We report a patient with vulvar lichen sclerosus, Langerhans cell histiocytosis (LCH), and later vulvar cancer. In LCH, high amounts of non functional Langerhans cells are present in the affected tissue, making it possible that LCH may have contributed to vulvar cancer development in this patient.

The prognostic value of blood and lymph vessel parameters in lichen sclerosus for vulvar squamous cell carcinoma development: an immunohistochemical and electron microscopy study.

OBJECTIVE: The objective of the study was to quantify vessel type and density in lichen sclerosus (LS) to find a marker for its malignant potential. STUDY DESIGN: Quantitative analysis was performed on paraffin-embedded tissue samples of 28 patients with LS (7 adjacent to vulvar squamous cell carcinoma, 21 solitary) and immunohistochemical staining for CD34 (vascular and lymphangiogenic lymph endothelial cells), D2-40 (lymphatic-specific marker), and alpha-SMA (pericyte marker). Electron microscopy was performed on fresh tissue. RESULTS: No significant differences in vessel density or other vessel parameters could be demonstrated between the 2 groups. In hyalinized lesions, vessel diameter, and alpha-SMA positivity was reduced compared with nonhyalinized lesions. Electron microscopy revealed detachment of pericytes from vascular endothelial cells and increased thickening of basement membrane, whereas endothelial cell function did not appear strongly impaired. CONCLUSION: Malignant potential of LS cannot be predicted by vessel characteristics. Hyalinization in LS is associated with pericyte detachment from the basal lamina of vascular endothelial cells.

Lichen sclerosus: treatment and follow-up at the departments of gynaecology and dermatology.

OBJECTIVE: To compare the treatment and follow-up of patients with lichen sclerosus (LS) at the departments of Gynaecology and Dermatology at the Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands, to evaluate the need for a multidisciplinary vulvar clinic. MATERIALS AND METHODS: Treatment and follow-up data of all women with histologically proven (between January 1995 and January 2001) anogenital LS visiting the outpatient clinics of the departments of Obstetrics & Gynaecology and Dermatology were collected (last date of follow-up: January 2008). RESULTS: Eighty-four patients with LS were included in this study, 10 patients (12%) of which were treated by both specialties. At the Gynaecology department, LS patients more often received surgical treatment, topical estrogens, and lidocaine ointment, whereas at the Dermatology department, local class 2/3 corticosteroids were more often prescribed. Follow-up frequencies were similar in both specialties and took place at 3 to 4 visits in the first year and at least once a year afterward. One patient developed vulvar squamous cell carcinoma. This patient had withdrawn from follow-up and had her condition diagnosed with carcinoma 74 months after the LS had been diagnosed. CONCLUSIONS: Although no hospital guidelines existed, management of patients with LS agreed with current recommendations in the literature, although differences in secondary and supportive therapy existed owing to differences in expertise. The relatively high percentage of patients treated by both specialties with a high frequency of visits emphasizes the need for a multidisciplinary clinic for vulvar disease.

Structured analysis of histopathological characteristics of vulvar lichen sclerosus in a juvenile population.

Genital lichen sclerosus (LS), a chronic noninfectious dermatosis, is not rare in pediatric dermatology. The histopathological diagnosis in children and adults in both genital and nongenital LS is considered to be the same and encompasses a broad range of possible characteristics. Clinical manifestations and treatment options of genital LS in children are different depending on gender. The vast majority of boys are treated with circumcision, making for a larger amount of information on the histopathology of genital LS in boys, whereas substantial information on the histopathology of juvenile vulvar LS is lacking. In girls, vulvar LS almost always persists beyond puberty and, therefore, presents a particular challenge to clinicians and cause for concern for the patient. Vulvar LS in childhood and adolescence (juveniles) is underreported, and there are uncertainties with regard to the long-term course of the disease when it occurs at an age when the vulva is still developing. The present study investigates biopsies of 100 juvenile cases of vulvar LS and analyzes the presence or absence of the most salient histopathological characteristics of LS that are described in the literature. We found that the range of histopathological characteristics known for adult LS are also present in juvenile vulvar LS, even at very young ages, including histopathological features associated with autoimmune disease, in support of the idea of a similar pathogenesis.

A panel of p16(INK4A), MIB1 and p53 proteins can distinguish between the 2 pathways leading to vulvar squamous cell carcinoma.

Two pathways leading to vulvar squamous cell carcinoma (SCC) exist. The expression of proliferation- and cell-cycle-related biomarkers and the presence of high-risk (hr) HPV might be helpful to distinguish the premalignancies in both pathways. Seventy-five differentiated vulvar intra-epithelial neoplasia (VIN)-lesions with adjacent SCC and 45 usual VIN-lesions (32 solitary and 13 with adjacent SCC) were selected, and tested for hr-HPV DNA, using a broad-spectrum HPV detection/genotyping assay (SPF(10)-LiPA), and the immunohistochemical expression of MIB1, p16(INK4A) and p53. All differentiated VIN-lesions were hr-HPV- and p16-negative and in 96% MIB1-expression was confined to the parabasal layers. Eighty-four percent exhibited high p53 labeling indices, sometimes with parabasal extension. Eighty percent of all usual VIN-lesions were hr-HPV-positive, p16-positive, MIB1-positive and p53-negative. Five (of seven) HPV-negative usual VIN lesions, had an expression pattern like the other HPV-positive usual VIN lesions. In conclusion, both pathways leading to vulvar SCC have their own immunohistochemical profile, which can be used to distinguish the 2 types of VIN, but cannot explain differences in malignant potential.

Underestimation of subfertility among relatives when using a family history: taboo bias.

Family history is widely used in clinical practice and research in order to study genetic aspects of disorders in general, and is recommended as a tool in the assessment of male subfertility. Unfortunately, little is known about the validity of this tool. In this survey, we sent questionnaires to 474 randomly selected men aged 25-40 years in order to collect data on subfertility among them and their relatives. A nonresponder study was also conducted in order to evaluate selection bias. A personal interview was also performed with some respondents in order to gauge how well the data corresponded with questionnaires that were returned. Two hundred forty-three men (51.3%) completed the questionnaire. The responders reported a significantly lower prevalence of subfertility among their relatives than among themselves. Among brothers, the reported prevalence was about 5 times lower (ie, 3.6%) than among responders (15.3%). The nonresponder study and personal interviews showed that these differences were not caused by a selective response to the survey or by the use of a questionnaire instead of a personal interview. We conclude that subfertility among relatives is severely underestimated through the use of family history, probably because of the taboo of discussing subfertility. Knowledge of subfertility may spread selectively within families, causing substantial misclassification. Therefore, researchers and clinicians should be aware that an inquiry of family history is likely to lead to underestimation of subfertility among relatives.

Phenotypic characteristics of male subfertility and its familial occurrence.

Genetic factors can attribute to male subfertility. A case-control study was carried out to investigate familial occurrence of male subfertility and the phenotypic characteristics of familial male subfertility. The medical data and family histories of 253 severely subfertile men who were candidates for intracytoplasmic sperm injection were compared to the data from 243 randomly selected men. The prevalence of male fertility problems among brothers and maternal uncles of subfertile men was significantly higher than among controls (brothers 10.4% vs 0.5% and maternal uncles 1.7% vs 0.2%). The phenotypes of subfertile men with a positive family history more often showed normal levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) compared to the phenotypes of subfertile men with a negative family history. In addition, subfertile men with a positive family history had a lower percentage of motile sperm. Genetic aberrations, including a chromosomal abnormality or a microdeletion of the Y chromosome, were present in 13.8% of the severely subfertile men. Male subfertility appears to have a familial occurrence, especially among brothers and maternal uncles. Furthermore, examination of the data suggests that subfertile men with a familial occurrence of male subfertility more often have normal levels of FSH and LH and a lower percentage of motile sperm.

High levels of p53 expression correlate with DNA aneuploidy in (pre)malignancies of the vulva.

The molecular pathogenesis of human papilloma virus-unrelated vulvar squamous cell carcinoma is not well known. Whether malignant progression of lichen sclerosus and differentiated vulvar intraepithelial neoplasia to vulvar squamous cell carcinoma could be accompanied by altered DNA content has not been studied extensively. DNA content in isolated nuclei of microdissected normal vulvar epithelium (n = 2), lichen sclerosus (n = 9), differentiated vulvar intraepithelial neoplasia (n = 13), and squamous cell carcinoma (n = 17) from 22 patients was measured via DNA image cytometry. For additional analysis, 6 differentiated vulvar intraepithelial neoplasia lesions were selected, bringing the number of patients to 28. p53 expression was determined by immunohistochemistry on consecutive tissue sections. Thirty-eight percent (5/13) of differentiated vulvar intraepithelial neoplasia lesions and 65% (11/17) of squamous cell carcinomas were DNA aneuploid or tetraploid. In lesions that contained differentiated vulvar intraepithelial neoplasia and adjacent squamous cell carcinoma, the ploidy status of differentiated vulvar intraepithelial neoplasia did not exceed that of squamous cell carcinoma. We observed a strong correlation between high p53 expression and DNA aneuploidy. This relation was also present at the level of a single nucleus, measured by sequential image cytometry of p53 immunohistochemistry followed by DNA image cytometry on formalin-fixed tissue sections. Similarly, we found p53-positive nonproliferating cells with increased DNA content in the superficial compartment of 6 additional solitary differentiated vulvar intraepithelial neoplasia lesions that were not associated with squamous cell carcinoma, indicating ascending aneuploid cells from the basal compartment. DNA ploidy measurements suggest that differentiated vulvar intraepithelial neoplasia has a higher malignant potential than lichen sclerosus and thus is a more likely precursor of squamous cell carcinoma. Furthermore, high p53 expression correlates with increased DNA content and aneuploidy; but it requires further research to unveil a possible causal relation.

Vulvar squamous cell carcinoma development after diagnosis of VIN increases with age.

OBJECTIVE: The purpose of the present study is to investigate the trends in incidence of both usual (u) and differentiated (d) vulvar intraepithelial neoplasia (VIN) separately, their malignant potential and the relation with other HPV related anogenital lesions in the Netherlands during a 14-year-period. METHODS: The incidences of both types of VIN and vulvar SCC were retrieved from the Nationwide Netherlands Database of Histo- and Cytopathology. Population data were retrieved from the Database of Statistics Netherlands. RESULTS: In the study period, the incidence of uVIN and dVIN increased, while the incidence of vulvar SCC remained stable. The overall percentage of uVIN patients that were later diagnosed with vulvar SCC was 5.7%, which was significantly lower than the percentage for dVIN patients (32.8%). In addition to this 5.6-fold increased conversion rate, the time of progression from dVIN to SCC development was significantly shorter than that of uVIN (p=0.005). Percentage of uVIN patients that were later diagnosed with SCC significantly increased with age (p=0.005), whereas the time to SCC significantly shortened with age (p=0.05). Forty-one percent of uVIN patients had a past, concomitant or future HPV-associated lesion of the lower genital tract, which is in contrast to the 3% for dVIN patients. CONCLUSIONS: An increase in diagnoses of both uVIN and dVIN has not led to an increase in vulvar SCC incidence. The malignant potential of dVIN is higher than that for uVIN. For uVIN the malignant potential increases with age.

MIB1 expression in basal cell layer: a diagnostic tool to identify premalignancies of the vulva.

Lichen sclerosus, high-grade usual vulvar intraepithelial neoplasia (VIN) and differentiated VIN have a different malignant potential. The objective of this study was to quantify the proliferative activity in the basal region of the epithelium of vulvar premalignancies. Furthermore, we investigated whether MIB1 expression in the basal region of vulvar epithelium can be helpful in diagnosing differentiated VIN, which may be hard to discern from normal epithelium. MIB1 was used to immunohistochemically visualise proliferating cells within formalin-fixed, paraffin-embedded, archival tissue sections of different vulvar premalignancies (N=48) and normal vulvar epithelium (N=16). Automatic digital image analysis software was developed to quantify the proliferating fraction in different parts of the epithelium (MIB1 positivity index). MIB1 expression differed among the various vulvar premalignancies; a MIB1-negative basal cell layer was a distinct feature of normal vulvar epithelium. No MIB1-negative basal cell layer was noted in differentiated VIN or other vulvar premalignancies. Owing to this negative cell layer, the MIB1 proliferation index in normal vulvar epithelium was significantly lower than in vulvar premalignancies. In conclusion, MIB1 expression can be a helpful tool in diagnosing a premalignancy and has additional value especially to distinguish differentiated VIN neoplasia from normal vulvar epithelium, but cannot explain the differences in malignant potential.