Proliferative verrucous vs conventional leukoplakia: no significantly increased risk of HPV infection

Personalized Medicine in Oral Oncology: Imaging Methods and Biological Markers to Support Diagnosis of Oral Squamous Cell Carcinoma (OSCC): A Narrative Literature Review

For decades, oral squamous cell carcinoma (OSCC) has been one of the most prevalent and mortal cancers worldwide. The gold standard for OSCC diagnosis is still histopathology but this narrative multidisciplinary review has the aim to explore the literature about conventional OSCC prognostic indicators related to the pTNM stage at the diagnosis such as the depth of invasion and the lymphovascular invasion associated with distant metastasis as indicators of poor life expectancy. Despite its multifactorial nature and recognizable precursors, its diagnosis at the early stages is still challenging. We wanted to highlight the importance of the screening as a primary weapon that a stomatologist should consider, intercepting all at-risk conditions and lesions associated with OSCC and its early stages. This narrative review also overviews the most promising imaging techniques, such as CT, MRI, and US-echography, and their application related to clinical and surgical practice, but also the most-investigated prognostic and diagnostic tissue and salivary biomarkers helpful in OSCC diagnosis and prognostic assessment. Our work highlighted remarkable potential biomarkers that could have a leading role in the future. However, we are still far from defining an appropriate and concrete protocol to apply in clinical practice. The hope is that the present and future research will overcome these limitations to benefit patients, clinicians, and welfare.

On the Oral Microbiome of Oral Potentially Malignant and Malignant Disorders: Dysbiosis, Loss of Diversity, and Pathogens Enrichment

The role of dysbiosis in the development and progression of oral potentially malignant disorders (OPMDs) remains largely unknown. Here, we aim to characterize and compare the oral microbiome of homogeneous leucoplakia (HL), proliferative verrucous leukoplakia (PVL), oral squamous cell carcinoma (OSCC), and OSCC preceded by PVL (PVL-OSCC). Fifty oral biopsies from HL (n = 9), PVL (n = 12), OSCC (n = 10), PVL-OSCC (n = 8), and healthy (n = 11) donors were obtained. The sequence of the V3-V4 region of the 16S rRNA gene was used to analyze the composition and diversity of bacterial populations. In the cancer patients, the number of observed amplicon sequence variants (ASVs) was lower and Fusobacteriota constituted more than 30% of the microbiome. PVL and PVL-OSCC patients had a higher abundance of Campilobacterota and lower Proteobacteria than any other group analyzed. A penalized regression was performed to determine which species were able to distinguish groups. HL is enriched in Streptococcus parasanguinis, Streptococcus salivarius, Fusobacterium periodonticum, Prevotella histicola, Porphyromonas pasteri, and Megasphaera micronuciformis; PVL is enriched in Prevotella salivae, Campylobacter concisus, Dialister pneumosintes, and Schaalia odontolytica; OSCC is enriched in Capnocytophaga leadbetteri, Capnocytophaga sputigena, Capnocytophaga gingivalis, Campylobacter showae, Metamycoplasma salivarium, and Prevotella nanceiensis; and PVL-OSCC is enriched in Lachnospiraceae bacterium, Selenomonas sputigena, and Prevotella shahii. There is differential dysbiosis in patients suffering from OPMDs and cancer. To the best of our knowledge, this is the first study comparing the oral microbiome alterations in these groups; thus, additional studies are needed.

Oral Squamous Papilloma Mimicking Oral Verrucous Leukoplakia

The human papillomavirus (HPV) is a non-enveloped DNA virus that causes a variety of skin and mucosal lesions. This report reviews a likely HPV-related lesion of oral squamous cell papilloma clinically mimicking oral verrucous leukoplakia. A 71-year-old white male presented with a raised white lesion on the palatal mucosa. It felt hard on palpation and had a sessile fixed base, and a rough verrucous surface. The lesion was fully excised. Histopathology showed short, thin, fingerlike projections lined by stratified squamous epithelium with thin central connective tissue cores. The epithelial superficial layers demonstrated focal koilocytotic changes suggestive of an HPV infection. High-risk HPV-related lesions have the potential to turn malignant. Early diagnosis and management are critical to preventing serious complications.

Malignant development of proliferative verrucous/multifocal leukoplakia: A critical systematic review, meta-analysis and proposal of diagnostic criteria

BACKGROUND

Proliferative verrucous/multifocal leukoplakia (PVML) is an oral potentially malignant disorder (OPMD) that exhibits high rates of malignant development (MD). This study aimed to analyse the risk of MD of PVML, as well as to investigate the possible risk factors associated with its malignization.

METHODS

A bibliographical search of the PubMed, Embase, Web of Science, and Scopus databases was conducted. PVML MD rates were calculated as a pooled proportion, and the risk factors were calculated as risk ratios, using fixed and random models based on the presence of heterogeneity.

RESULTS

From a total of 417 records, 16 articles were retrieved for inclusion. The subgroup analysis revealed a higher MD rate in the studies that were conducted in America, and, likewise, said studies involved a longer follow-up time (>6 years). There was a non-significant lower risk of malignization among males. A negative correlation was observed between MD and the year in which the studies were published.

CONCLUSIONS

The pooled MD of PVML was 65.8% (95% CI: 55.3-76.2, p < 0.001). Prospective studies of PVML must be designed using simple and universal clinical diagnostic criteria to be able to make an early diagnosis of this important OPMD and acknowledge the frequency of MD.

Prognosis Parameters of Oral Carcinomas Developed in Proliferative Verrucous Leukoplakia: A Systematic Review and Meta-Analysis

Simple Summary

Proliferative verrucous leukoplakia is considered by the WHO as an oral potentially malignant disorder that presents the highest tendency to recurrence and malignant transformation rate. However, to date limited evidence-based prognostic data for oral carcinomas developed in patients with proliferative verrucous leukoplakia (PVL-OC) have been published, and these carcinomas probably perform better than conventional oral carcinomas. In this study we present a systematic review and meta-analysis to evaluate the current evidence in relation to the prognosis of oral carcinomas developed in patients PVL-OC.

Abstract

Proliferative verrucous leukoplakia (PVL) is contemplated by the World Health Organization (WHO) as an oral potentially malignant disorder (OPMD) with a high the highest malignant transformation ratio among all OPMD (approximately 50%). Our aim was to evaluate the current evidence in relation to the prognosis of oral carcinoma developed in patients with proliferative verrucous leukoplakia (PVL-OC). We searched PubMed, Embase, Web of Science and Scopus for published studies (upper date limit = June 2021). We evaluated the quality of studies (QUIPS tool). We carried out meta-analyses, examined inter-study heterogeneity through subgroup and meta-regression analyses, and performed sensitivity and small-study effects analyses to test the stability and reliability of results. 23 studies met inclusion criteria (505 patients with PVL, of which 288 developed a total of 504 carcinomas). The meta-analyzed overall mortality rate was 21.29% (pooled proportions [PP] = 95% confidence intervals [CI] = 8.77–36.36) for PVL-OC, clearly lower than the 34.7–50% mortality rate for conventional oral cancer reported in previous studies. In comparison with a single study reporting on conventional oral cancers, mortality was significantly lower for PVL-OC (hazard ratio = 0.29 [95%CI = 0.10–0.89], p = 0.03). Univariable meta-regression verified that case series that presented higher proportions of verrucous carcinomas showed a better survival of PVL-OC (p = 0.05), but not with higher proportion of oral squamous cell carcinomas (p = 0.74). Significant differences were not found for other relevant variables such as follow up period (p = 0.44) or multiple tumor development (p = 0.74). In conclusion, PVL-OC show favorable prognostic parameters, especially with regard to the mortality rate.

Oral Proliferative Verrucous Leukoplakia: Progression to Malignancy and Clinical Implications. Systematic Review and Meta-Analysis

Simple Summary

Proliferative verrucous leukoplakia (PVL) was recognized in 2005 by the World Health Organization as a rare subtype of true oral leukoplakia, with unknown etiology. Since its first description in 1985, several diagnostic criteria have been proposed over the years. The aim of this systematic review is to investigate the percentage of patients diagnosed with proliferative verrucous leukoplakia who progressed to oral verrucous carcinoma (OVC) or conventional oral squamous cell carcinoma (OSCC).

Abstract

Aim: The aim of the present systematic review was to investigate the risk of malignant transformation of proliferative verrucous leukoplakia (PVL). Materials and Methods: the search was carried out using a combination of terms (leukoplakia OR leucoplakia) AND (multifocal OR proliferative) on the following databases: PubMed, Scopus, Web of Science (WOS Core Collection), Cochrane Library, selecting only articles published since 1985 and in the English language. Demographic, disease-related, and follow-up data extracted from the studies included in the qualitative synthesis were combined. Weighted means ± standard deviations were calculated for continuous variables, while categorical variables were reported as frequencies and percentages. Dichotomous outcomes were expressed as odd ratios (ORs) with 95% confidence intervals (CIs). Odd ratios for individual studies were combined using a random-effects meta-analysis, conducted using Review Manager 5.4 Software (Cochrane Community, Oxford, England). Results: twenty-two articles were included, with a total of 699 PVL patients, undergoing a mean follow-up of 7.2 years. Sixty-six percent of patients were females, with a mean age of 70.2 years, and 33.3% were males, with a mean age of 59.6 years. Most patients were non-smokers and non-alcohol users, and the gingiva/alveolar ridge mucosa was the most involved anatomical site by both PVL appearance and malignant transformation. A total of 320 PVL patients developed oral verrucous carcinoma (OVC) or conventional oral squamous cell carcinoma (OSCC) because of malignant transformation of PVL lesions (45.8%). A statistically significant 3.8-fold higher risk of progression to conventional OSCC was found compared to OVC in PVL patients, with women being 1.7 times more likely to develop oral cancer than men, as a consequence of PVL progression. Moreover, a statistically significant higher likelihood of developing conventional OSCC in female PVL patients than in males was found. In 46.5% of patients with PVL malignant transformation, multiple carcinomas, in different oral sites, occurred during follow-up. Conclusions: PVL is an aggressive lesion, which, in a high percentage of cases (almost 50%), undergoes malignant transformation, mainly toward OSCC. The female gender is most affected, especially in the elderly, with a negative history for alcohol and tobacco consumption.

A Scoping Review on Gaps in the Diagnostic Criteria for Proliferative Verrucous Leukoplakia: A Conceptual Proposal and Diagnostic Evidence-Based Criteria

Proliferative verrucous leukoplakia (PVL) is considered as an oral potentially malignant disorder (OPMD) that presents with a high tendency to recurrence after treatment and has the highest malignant transformation ratio among all OPMD (50%). Evidence-based publications have indicated that the malignant evolution reported is significantly related to the inconsistent diagnostic criteria used in primary-level studies; so, it has been hypothesized that the risk of oral cancer for this disease could even be underestimated. This is important because PVL requires specific management protocols, evidence-based, aimed at the early diagnosis of cancer developing in these lesions. We present a scoping review-a novel approach to mapping the available literature on a given topic to provide an overview of the available research evidence and to highlight possible gaps in the evidence-especially related in our study to the diagnostic aspects of PVL, and to issue a conceptual proposal and diagnostic criteria for PVL. We conclude that PVL is a white, multifocal and progressive lesion with a high malignant transformation rate which is diagnosed mainly around the age of 60 years without any specific histological characterization. We also advise a personal reflection on the level of certainty with which the clinician makes the diagnosis of a particular case of PVL.

Oral microbiome in Proliferative Verrucous Leukoplakia exhibits loss of diversity and enrichment of pathogens

OBJECTIVES

Oral microbiome plays an important role in oral diseases. Among them, proliferative verrucous leucoplakia (PVL) is an uncommon form of progressive multifocal leukoplakia with a worryingly rate of malignant transformation. Here, we aimed to characterize the oral microbiome of PVL patients and compare it with those of healthy controls.

MATERIAL AND METHODS

Oral biopsies from ten PVL patients and five healthy individuals were obtained and used to compare their microbial communities. The sequence of the V3-V4 region of 16S rRNA gene was used as the taxonomic basis to estimate and analyze the composition and diversity of bacterial populations present in the samples.

RESULTS

Our results show that the oral microbial composition and diversity are significantly different among PVL patients and healthy donors. The average number of observed operational taxonomic units (OTUs) was higher for healthy donors than for PVL, proving a loss of diversity in PVL. Several OTUs were found to be more abundant in either group. Among those that were significantly enriched in PVL patients, potential protumorigenic pathogens like Oribacterium sp. oral taxon 108, Campylobacter jejuni, uncultured Eubacterium sp., Tannerella, and Porphyromonas were identified.

CONCLUSION

Oral microbiome dysbiosis was found in patients suffering from PVL. To the best of our knowledge, this is the first study investigating the oral microbiome alterations in PVL and, due to the limited number of participants, additional studies are needed. Oral microbiota-based biomarkers may be helpful in predicting the risks for the development of PVL.

High-Dose-Rate Brachytherapy for Primary Treatment of Refractory Proliferative Verrucous Leukoplakia of the Hard Palate

Oral proliferative verrucous leukoplakia (PVL) is a rare, progressive form of leukoplakia with a high rate of malignant transformation. No therapies are known to lower the rate of malignant transformation and prevent a recurrence.

An 84-year-old patient with a years-long history of symptomatic PVL of the hard palate refractory to CO2 laser ablation presented to the radiation oncology clinic for consideration of non-surgical management. High dose rate brachytherapy was used to deliver 36 Gy in 12 fractions to the hard palate using an Ir-192 source with a custom-molded applicator.

By three months of follow-up, the patient had complete regression of the PVL and resolution of acute mucositis. With 18 months of follow-up, the patient remains disease- and symptom-free without toxicities of treatment.

High dose rate surface applicator brachytherapy is a feasible and potentially effective treatment for oral PVL, yielding durable control with low long-term toxicity.

Recurrences following treatment of proliferative verrucous leukoplakia: A systematic review and meta-analysis

BACKGROUND

A systematic review and meta-analysis were made of the incidence of recurrences in patients with proliferative verrucous leukoplakia (PVL) subjected to different types of treatment.

METHODS

The study was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines. A literature search was made in the Medline (PubMed), EMBASE, and Web of Science databases, together with a manual search, covering the period from 1985 to January 2020, with no language restrictions. Studies were included if they described treatments applied to at least 10 patients with the corresponding outcomes. Methodological quality was evaluated using Jadad scale and Newcastle-Ottawa tool. Global incidence was calculated by random effects meta-analysis using the Comprehensive Meta-analysis version 3.0 software. Publication bias was assessed using funnel plots and the Duval and Tweedie trim and fill method.

RESULTS

Of the 922 identified articles, 12 were found to meet the inclusion criteria. Most of them presented moderate or low risk of bias. A total of 397 patients were analyzed. The mean age was 62.34 years and 248 were women (62.5%). The mean follow-up was 79.3 months. The most frequent treatment was surgical removal with a cold scalpel or laser (339 patients). A total of 232 subjects presented lesion recurrence. The combination of proportions global effect meta-analysis yielded a recurrence rate of 67.2% (95% CI: 48.3-81.8), with the absence of publication bias.

CONCLUSIONS

There is not enough scientific evidence to conclude that any treatment strategy is able to reduce the recurrence in PVL.

Differentially methylated genes in proliferative verrucous leukoplakia reveal potential malignant biomarkers for oral squamous cell carcinoma

OBJECTIVES

To explore the pathophysiology of proliferative verrucous leucoplakia (PVL) through a methylated DNA immunoprecipitation and high-throughput sequencing (MeDIP-seq) case-control study.

MATERIALS AND METHODS

Oral biopsies from ten PVL patients and five healthy individuals were obtained and used to compare their epigenetic patterns. Network biology methods and integrative analyses of MeDIP-seq and RNAseq data were applied to investigate functional relations among differentially methylated genes (DMGs). The value of selected genes as malignant biomarkers was evaluated in a large cohort of oral squamous cell carcinoma (OSCC) patients from TCGA.

RESULTS

A total of 4647 differentially methylated regions were found, with a prominent state of hypermethylation in PVL patients. At the gene level, differentially methylated regions (DMRs) covered 826 genes with distinct roles, including transcription factors and binding proteins with functions in cell adhesion, migration, proliferation, regulation of transcription, bone morphogenesis, and cell signalling. Network analysis revealed three major hubs, two of them collecting proteins related to the response of the patients to PVL and treatment and one hub collecting proteins related to PVL and cancer. The integrative analysis revealed 8 genes (ARTN, CD8A, GATA3, HOXD10, MYO7A, OSR2, PLCB1, and SPOCK2) significantly upregulated in PVL compared to control and 5 genes (ANKRD6, DLG2, GPX3, PITX2, and ZNF736) significantly downregulated. The status of de-regulation found for PVL patients was concordant with what was found for OSCC samples compared to normal adjacent tissue.

CONCLUSION

Our findings show the potential of methylation markers in PVL and suggest novel OSCC diagnostic biomarkers which may boost the development of novel epigenetic-based therapies.

Immune expression profile identification in a group of proliferative verrucous leukoplakia patients: a pre-cancer niche for oral squamous cell carcinoma development

OBJECTIVES

To explore the pathophysiology of proliferative verrucous leukoplakia, a rare oral disorder that exhibits high rates of recurrence and malignant transformation, through a RNAseq case-control study.

MATERIAL AND METHODS

We obtained oral biopsies from 10 patients with verrucous leukoplakia lesions and from the mucosa of 5 healthy individuals for sequencing using RNAseq technology. Using bioinformatic methods, we investigated gene expression and enrichment differences between patients both with and without the disorder. We applied network biology methods to investigate functional relations among those genes that were differentially deregulated.

RESULTS

We detected 140 differentially expressed genes with distinct roles in immune surveillance, tissue and organ morphogenesis, development, and organization. Of these 140 genes, 111 have been previously described as cancer expression biomarkers, being oral squamous cell carcinoma the most represented type of cancer among them. Of these 140 genes, 26 were prioritized for further investigation as biomarkers using larger sample sizes.

CONCLUSIONS

The gene expression patterns of healthy and unhealthy patients differed in 140 genes whose deregulation has a functional impact on normal functioning of the immune system. This immune expression profile provides a plausible hypothesis to explain the transformation to oral squamous cell carcinoma observed in 6 of the 10 assayed cases.

CLINICAL RELEVANCE

By determining the molecular bases of the proliferative verrucous leukoplakia disorder and identifying early biomarkers of malignancy, this can allow us to develop new treatment strategies.

Malignant transformation of oral proliferative verrucous leukoplakia: a series of 48 patients with suggestions for management

Proliferative verrucous leukoplakia (PVL) is a rare and refractory form of oral mucosal leukoplakia of unknown origin, characterized by high rates of malignant transformation. Different diagnostic criteria, terminologies, and therapeutic approaches have been proposed since the first report in 1985. There remains no general agreement regarding the clinical and histological diagnosis, prevention, and correct management of this disease. This retrospective study investigated 48 patients affected by PVL showing at least one malignant transformation and followed up at 2-month intervals. Twenty-five were female (52.1%) and 23 (47.9%) were male; their median age was 67 years (range 40-93 years). Follow-up ranged from 18 to 240 months. Clinical examination included the use of Lugol's solution to prevent clinical underestimation of the margins and toluidine blue for suspicious areas. Surgical excision by scalpel was the preferred treatment for suspicious lesions, with only five carcinomas surgically removed by diode laser and two by CO₂ laser. All specimens were accurately mapped after formalin fixation. Fifteen patients (31.3%; 10 female, five male) developed one oral carcinoma, while 33 (68.7%) developed two or more primary tumours (range 3-12). Only four patients (8.3%), who developed between 2 and 8 oral squamous cell carcinomas (OSCCs), died of tumour-related causes. The pre-surgical clinical workup, subsequent surgical treatment, and follow-up are key to success for patients affected by PVL with malignant transformation into stage 1 OSCC and/or verrucous carcinoma, leading to a high overall survival rate.

Potentially malignant disorders of the oral cavity and oral dysplasia: A systematic review and meta-analysis of malignant transformation rate by subtype

IMPORTANCE

Potentially malignant disorders of the oral cavity (OPMD) are a heterogeneous group of lesions associated with a variable risk of malignant transformation (MT) to invasive cancer. Leukoplakia (LE), lichen planus (LP), oral lichenoid lesions (OLL), oral erythroplakia (OE), oral submucous fibrosis (OSF), and proliferative verrucous leukoplakia (PVL) are among the most common of these lesions. Oral dysplasia is a mucosal area characterized by cellular and architectural derangement, which may be associated with OPMDs or not.

OBJECTIVE

To define the MT rate of OPMDs and the risk of development into cancer of mild vs moderate/severe oral dysplasia. This in order to implement adequate follow-up strategies and treatment decisions.

STUDY DESIGN

We performed a systematic review and meta-analysis on studies reporting the MT rates of OPMDs and oral dysplasia. Ninety-two studies were included for the analysis. Cumulative rates were reported for OPMDs overall and as a subgroup, a comparison was made of mild vs moderate/severe dysplasia. Meta-regression on OPMD and year of publication was also performed.

MAIN OUTCOME AND MEASURES

Overall MT rates of OPMDs and odds ratio of MT of mild vs moderate/severe dysplasia.

RESULTS

Overall MT rate across all OPMD groups was 7.9% (99% confidence interval [CI] 4.9%-11.5%). MT rates of the specific OPMD subgroups were as follows: LP 1.4% (99% CI 0.9%-1.9%), LE 9.5 (5.9%-14.00%), OLL 3.8% (99% CI 1.6%-7.00%), OSF 5.2% (99% CI 2.9%-8.00%), OE 33.1% (99% CI 13.6%-56.1%), and PVL 49.5% (99% CI 26.7%-72.4%). Regarding the dysplasia grades comparison, the meta-analysis showed that moderate/severe dysplasia is meaningfully associated to a much greater risk of MT compared to mild dysplasia with an odds ratio of 2.4 (95% CI 1.5-3.8) [Correction added on 27 December 2019, after first online publication: CI updated from 99% to 95%.]. Heterogeneity was not significant. Annual MT rates were approximated based on the average follow-up as reported in the various subgroups. Lichen planus had an annual MT of 0.28%, OLL of 0.57%, leukoplakia of 1.56%, PVL of 9.3%, and OSF of 0.98%. Mild dysplasia had an annual MT of 1.7%, while severe dysplasia of 3.57%. Meta-regression showed a significant negative correlation of PVL MT rate and year of the study (P value <.001).

CONCLUSIONS AND RELEVANCE

OPMDs and oral dysplasia are relatively common conditions that general practitioners, head and neck, and oral medicine specialists, face in their everyday practice. Our analysis confirms the significant risk of MT of these lesions, although variable among the subgroups. Moderate/severe dysplasia bears a much higher risk of cancer evolution than mild dysplasia. It is important to raise public health awareness on the MT rates of these conditions, at the same time efficacious communication with the patient is of utmost importance. This, coupled with strict follow-up measures and optimal treatment strategies, would help in reducing the transformation of these oral conditions into invasive cancer.

Clinicopathologic analysis of verrucous hyperplasia, verrucous carcinoma and squamous cell carcinoma as part of the clinicopathologic spectrum of oral proliferative verrucous leukoplakia: A literature review and analysis

OBJECTIVE

Proliferative verrucous leukoplakia is classified as a potentially malignant disorder because of its high rate of malignant transformation. PVL progresses in a series of clinical stages where the early stage represents multiple, multifocal leukoplakias with a high recurrence rate. The intermediate and late stages are clinically exophytic lesion, diagnosed microscopically as verrucous hyperplasia that often progresses into verrucous carcinoma and/or squamous cell carcinoma. There is no single histologic definition and the diagnosis is retrospective following observed progression of the disorder. The goal of the current study was to conduct a literature review and analysis of PVL in the later stages to gain further knowledge on their clinicopathologic features.

DATA SOURCES

Medline's PubMed and Google Scholar were searched for adequately documented cases from 1985 to 2018. References of published articles were searched for additional cases.

REVIEW METHODS

Overall, 57 manuscripts were analyzed. 35/57 manuscripts provided adequate data on the clinicopathologic features in the premalignant and malignant stages.

RESULTS

Malignant transformation rate was 50% (average of 57 months). Gingiva, palate and buccal mucosa were the most common locations. Clinicopathologic features included; well differentiated carcinoma (78%), perineural invasion (3%), lymph node metastasis (4%); distant metastasis (0%), average duration of illness (65 months), DOD-dead of disease (44%). Moderate dysplasia, severe dysplasia and carcinoma in situ were exceptionally uncommon in the premalignant stages (0.8%).

CONCLUSION

Prognostic factors such as perineural invasion, lymph node metastasis and distant metastasis were uncommon occurrences which may have practical implications on treatment. Further studies are needed to substantiate our findings.

Second primary tumors in proliferative verrucous leukoplakia: a series of 33 cases

OBJECTIVES

To describe the number of second primary malignancies in a series of 33 patients with proliferative verrucous leukoplakia (PVL), detailing the mean time between primary malignancies and their clinical characteristics.

MATERIALS AND METHODS

Two groups of patients were included in this study: group 1 comprised 33 PVL patients who had developed ≥ 2 oral squamous cell carcinoma (OSCC) and group 2 comprised 48 PVL patients without malignant degeneration. We compared the groups with regard to age, gender, oral location, and number of oral sites affected. For patients in group 1, we determined the locations, clinical forms, and TNM stages of oral cancers. We also recorded the intervals of time between instances of oral cancer for all patients.

RESULTS

The groups did not differ significantly in age; however, group 1 included more women (p < 0.05). The follow-up period and number of oral PVL locations were greater in group 1 (p < 0.01). Moreover, in group 1, as the number of OSCCs increased, the intervals between them became shorter. The gingiva was the most common site. The mean number of cancers in group 1 was 3.15; five second primary tumors were diagnosed in one patient.

CONCLUSIONS

Multiple cancers in PVL patients were more frequently located on the gingiva in the form of erythroleukoplastic areas. In addition, the interval between new cancers decreased over time.

CLINICAL RELEVANCE

This is the series with the highest number of cases described with second primary tumors in PVL.

Diode laser surgery in the treatment of oral proliferative verrucous leukoplakia associated with HPV-16 infection

Background

Proliferative verrucous leukoplakia (PVL) is an oral potentially malignant disorder, characterized by multifocal expression, progressive clinical evolution, and a high rate of malignant transformation. Evidence-based information regarding optimal PVL management is lacking, due to the paucity of data. The present report describes a case of PVL associated with HPV-16 infection and epithelial dysplasia treated by diode laser surgery, and the outcome of disease clinical remission over a 2-year follow-up period.

Case report

A 61-year-old Caucasian male with oral verrucous hyperkeratosis presented for diagnosis. The lesions were localized on the maxillary gingiva and palatal alveolar ridge. Multiple biopsy specimens have been taken by mapping the keratotic lesion area. Microscopic examination was compatible with a diagnosis of PVL with focal mild dysplasia, localized in the right maxillary gingiva. Polymerase chain reaction (PCR) was done for human papillomavirus (HPV) detection which revealed presence of HPV DNA, and the genotype revealed HPV 16 in the sample. The PVL in the right gingival area was treated on an outpatient basis by excision with a diode laser. This approach resulted in good clinical response and decreased morbidity over a 2-year follow-up period.

Conclusions

This case illustrates the benefit of a conservative approach by diode laser treatment than wide surgical excision for management of the PVL lesions associated with mild dysplasia and HPV-16 infection.

Proliferative leukoplakia: Proposed new clinical diagnostic criteria

OBJECTIVE

We aimed to characterize proliferative verrucous leukoplakia (PVL) from a clinical and histopathological standpoint and suggest an updated classification.

SUBJECTS AND METHODS

Records of patients seen at three oral medicine centers with a clinical diagnosis of PVL were reviewed for clinical and histopathological features and malignant transformation (MT).

RESULTS

There were 42 patients (median age: 69 years [range: 36-88]; 35 females). 12.2% were current smokers. Family history of cancer was present in 43.7% of patients. Partial demarcation of lesion margins was present in 31.3% of lesions, followed by verrucous (27.5%), smooth (22.7%) erythematous (22.3%), and fissured (18.3%) appearance. Large and contiguous and multisite and non-contiguous lesions comprised 57.1% (24/42) and 35.7% (15/42) of PVL cases, respectively. 19.1% had prominent erythema (erythroleukoplakia). The most common histopathological diagnosis at first visit was hyperkeratosis without dysplasia (22/42; 56.4%). MT occurred in 71.4% patients after a median of 37 months [range: 1-210] from initial visit; erythroleukoplakia exhibited MT in 100% of cases.

CONCLUSION

The generic term "proliferative leukoplakia (PL)" may be more appropriate than PVL because 18.3% were fissured and 22.7% erythematous. We also propose the term proliferative erythroleukoplakia to more accurately describe the subset of PL with prominent erythema, which had the highest MT rate.

A Retrospective 20-Year Analysis of Proliferative Verrucous Leukoplakia and Its Progression to Malignancy and Association with High-risk Human Papillomavirus

Proliferative verrucous leukoplakia (PVL) is defined as an aggressive, relentless and recalcitrant form of leukoplakia that has a high propensity for malignant transformation. The aim of this study was to evaluate the malignant potential of PVL and determine its possible association with high-risk human papillomavirus (HPV). Twenty cases with a clinical and biopsy proven diagnosis of PVL were collected from the University of Florida Oral Medicine clinic database. Immunohistochemistry was performed to evaluate the expression of p16^INK4A and p53 genes in the PVL lesions. The lesions were also tested for high-risk HPV by DNA in-situ hybridization. The average age of the patients at the time of first biopsy was 62.7 years. Most patients had multiple sites of involvement, gingiva being the most common location. The lesions progressed to malignancy in approximately 50% of patients. The expression of p16^INK4A gene was considered negative, with at least a 50-65% immunoreactivity observed in only three cases that progressed to malignancy. No expression of high-risk HPV was detected, whereas p53 staining was positive in less than 25% of the cells demonstrating gene expression. No definite association between PVL and high-risk HPV infection could be established. Due to the high transformation potential of PVL, early recognition with aggressive treatment, including multiple biopsies, and continued close clinical follow-up, remain the mainstay of favorable management of this condition.

Oral leukoplakia and proliferative verrucous leukoplakia: a review for dental practitioners

Objectives To provide an overview of the current thinking in terms of the diagnosis and management of oral leukoplakia and proliferative verrucous leukoplakia as relevant to general dental practitioners.Data sources, data selection, data extraction, data synthesis We searched the MEDLINE Ovid, EMBASE databases and the Cochrane Library, (1990 to 16 April 2017), restricting our search to English language with the following key words: leukoplakia, white patch, proliferative verrucous leukoplakia, precancerous lesion, premalignant lesions, potentially malignant oral conditions and potentially malignant oral disorders. The two authors selected key papers and engaged in collaborative data extraction and synthesis of the selected reference material.Conclusions General dental practitioners (GDPs) are likely to encounter patients with a known or yet undiagnosed oral leukoplakia in their clinical practice. The diagnosis is clinically based as there are no pathognomonic histopathological features. The definition of leukoplakia has evolved over the years. The importance of recognition and appropriate management relating to this condition is described particularly as it is one of the oral potentially malignant lesions. The inferred increased risk of malignant transformation is well documented however controversy still persists in terms of the appropriate management for these lesions. Proliferative verrucous leukoplakia is a recalcitrant, often widespread and multifocal distinct type of leukoplakia. It is considered to have a high rate of malignant transformation with implications in terms of lifelong monitoring both clinically and histopathologically. A high index of suspicion is important for general dental practitioners in order to identify such lesions that would require onward referral for further investigation and management.

Evaluation and Management of Oral Potentially Malignant Disorders

Oral potentially malignant disorders (OPMDs) refer to epithelial lesions and conditions with an increased risk for malignant transformation; oral leukoplakia is the most commonly encountered. Overall, OPMDs have a low risk for malignant transformation, yet the challenge is the difficulty to reliably identify and predict which patients with OPMDs are at the highest risk for malignant transformation. Future research is needed to elucidate the molecular aspects of OPMDs, to improve current diagnostic strategies, leading to personalized management.

Management of proliferative verrucous leukoplakia: Justification for a conservative approach

BACKGROUND

Proliferative verrucous leukoplakia (PVL) is a progressive, multifocal, exophytic form of leukoplakia with high rates of malignant transformation. The purpose of this study was to evaluate a cohort of patients with PVL in a single tertiary referral clinic.

METHOD

Cases meeting accepted diagnostic criteria were reviewed with regard to their pathology, demographic characteristics, management, and outcomes. Human papillomavirus (HPV) testing was undertaken on a subset.

RESULTS

Almost half of the 48 patients with PVL (48%; n = 23) underwent malignant transformation after a median 23.4 months. The characteristics of this cohort were similar to those previously described, but management was notably more conservative. Conservative management of PVL was used in 92% of our patients, but the clinical outcomes seem comparable with previously described cohorts in which PVL was predominantly treated by surgical excision. All HPV testing was negative.

CONCLUSION

Aggressive surgical intervention in the premalignant phase of PVL may not influence the rate of malignant transformation.

Proliferative verrucous leukoplakia: diagnosis, management and current advances

Introduction

Proliferative verrucous leukoplakia is a multifocal and progressive lesion of the oral mucosa, with unknown etiology, and commonly resistant to all therapy attempts with frequent recurrences. It is characterized by a high rate of oral squamous cell carcinoma and verrucou carcinoma transformations.

Objective

To analyze the studies about Proliferative verrucous leukoplakia and develop a concise update.

Methods

A Pubmed search identifying studies (laboratory research, case series and reviews of literature) that examined patients with Proliferative verrucous leukoplakia was realized.

Results

There are not enough studies about Proliferative verrucous leukoplakia in the literature. The few found studies not present a consensus about its etiology and diagnosis criteria. Although several treatment strategies have been proposed, most of them still show a high recurrence rate.

Conclusion

More research about Proliferative verrucous leukoplakia is necessary to understand and treat this disease.

[Precancerous lesions of the buccal epithelium]

Squamous cell carcinomas of the oral cavity and lips consistently have a high incidence (they constitute the fifth most common form of cancer in France) and carry a heavy prognosis, particularly if diagnosed late. According to different studies, between 10 and 80% of such carcinomas occur in a pre-existing or precancerous lesion. The World Health Organisation (WHO) recommends the use of two terms for such lesions: precursor lesions, i.e. histological lesions associated with intraepithelial neoplasia (IEN) and verrucous hyperplasia (VH), frequently resulting clinically in leukoplakia or erythroplakia; "at risk" lesions, which include lichen planus, submucosal oral fibrosis and certain forms of genodermatosis.

Low expression of angiotensinogen and dipeptidyl peptidase 1 in saliva of patients with proliferative verrucous leukoplakia

AIM

To elucidate the profile of the salivary proteome.

METHODS

Unstimulated whole mouth saliva was collected from 30 volunteers [15 proliferative verrucous leukoplakia (PVL) patients and 15 controls] and proteins were submitted for mass spectrometry-based proteomics using the discovery approach, followed by analyses of variance and logistic regression tests.

RESULTS

A total of two hundred and eighty-three proteins were confidently identified in saliva. By combining two low abundance proteins from the PVL group, angiotensinogen (AGT) and dipeptidyl peptidase 1 (DPP1), a model for group differentiation was built with a concordance index of 94.2%, identifying both proteins as potential etiologic biomarkers for PVL.

CONCLUSION

This study suggests that both AGT and DPP1 may be involved in developmental mechanisms of PVL.

[Proliferative verrucous leukoplakia: Three cases and literature review]

BACKGROUND

The aim of this study was to collect epidemiological, aetiopathogenic, clinical, histological and therapeutic data concerning proliferative verrucous leucoplakia (PVL) and to report three new cases.

PATIENTS AND METHODS

A literature review performed using the Medline database enabled us to collate 39 studies involving 607 cases. Three new cases were added.

RESULTS

PVL is a rare disease characterized by extensive and multifocal oral leucoplakic lesions. Its histological pattern depends on the stage of the disease: hyperkeratosis, verrucous hyperplasia, verrucous carcinoma and squamous cell carcinoma. The aetiopathogenesis of PVL is poorly understood and there is no clear consensus concerning therapy. Malignant transformation occurs in over 50 % of cases.

DISCUSSION

Diagnosis of PVL is difficult because of the presenting signs, which can be mistaken for those of other diseases. Management may be complicated and long-term follow-up is essential.

Human papillomavirus infection in the oromaxillofacial area: Clinical anatomy and histological considerations

Clinical manifestations of human papillomavirus (HPV) infection in the head and neck can range from benign lesions, which are the most frequent, to malignant lesions. The prevalence of head and neck cancer is increasing, despite currently decreasing trends in known risk factors such as smoking and alcohol use. A new patient profile has appeared in recent practice: most frequently a middle-aged male patient who does not smoke or drink alcohol, is sexually active (possibly having multiple partners), and presents with oral or cervicofacial lesions requiring diagnosis and treatment. Another risk factor that should be considered in these patients is HPV infection. The association of oral potentially malignant disorders (OPMD) with HPV is a challenge for the medical practitioner. The gold standard for diagnosis is histopathological examination, which can also yield evidence suggesting HPV infection. Determination of the viral genotype provides additional data for assessing the oncological risk of an HPV infection. Treatment of these patients is aimed at removing the lesions, in association or not with antiviral treatment and recurrence control.

Role of human papillomavirus in oral squamous cell carcinoma and oral potentially malignant disorders: A review of the literature

Human papillomaviruses (HPVs) are epitheliotropic viruses with an affinity for keratinocytes and are principally found in the anogenital tract, urethra, skin, larynx, tracheobronchial and oral mucosa. On the basis of high, but variable frequency of HPV in oral squamous cell carcinoma (OSCC), malignant potential of HPV infection has been hypothesized but not definitely confirmed. The aim of this review was to highlight the genomic structure and possible mechanism of infection and carcinogenesis by HPV in the oral mucosa and to review the frequency of HPV prevalence in OSCC and oral potentially malignant disorders. A computer database search was performed through the use of PubMed from 1994 to 2014. Search keywords used were: HPV and oral cancer, HPV and oral leukoplakia, HPV and oral lichen planus, HPV and OSCC, HPV and verrucous carcinoma, HPV and proliferative verrucous leukoplakia, HPV and oral papilloma.

Optimal Management of Proliferative Verrucous Leukoplakia

Objective

Proliferative verrucous leukoplakia (PVL) is a rare and recalcitrant form of leukoplakia. The purpose of this review is to further characterize the risk factors, clinical course, and optimal treatment for this highly aggressive, premalignant lesion.

Data Sources

Twenty-six articles on PVL with a total of 329 PVL cases.

Review Methods

A systematic review of the literature using Ovid, PubMed, Cochrane Database, and gray literature was conducted of all PVL cases reported between 1985 and 2014. Inclusion criteria required reporting of patient follow-up and recurrence rates. Data were analyzed using descriptive statistics. Student t test and Fisher exact test were used to identify factors associated with malignant transformation.

Results

The mean patient age was 63.9 years. Most patients were female (66.9%) and nontobacco users (65.22%). Mean follow-up was 7.4 years, with an average of 9.0 biopsies per patient during this period. Proliferative verrucous leukoplakia exhibited histopathologic features along a progressive spectrum, evolving from leukoplakia to verrucous hyperplasia and ultimately invasive carcinoma. Surgery was the most common treatment implemented, but recurrence rates among 222 patients reached 71.2%. Subgroup analysis of 277 patients identified a 63.9% malignant transformation rate, and 39.6% of patients died of their disease. Age, sex, and tobacco use were not identified as risk factors associated with progression to cancer.

Conclusions

Proliferative verrucous leukoplakia is a rare form of leukoplakia with a high rate of malignant transformation. It necessitates high clinical suspicion, to include a lifetime of close follow-up and repeat biopsies by a health care provider well versed in oral carcinoma.

Oral proliferative verrucous leucoplakia: are there particular features for such an ambiguous entity? A systematic review

Proliferative verrucous leucoplakia (PVL) is a distinct, particularly aggressive form of oral leucoplakia. Given the low prevalence of PVL, data are sparse and are mostly from case reports, case series and only a few case-control studies, meaning that the literature is able to provide only weak evidence. The present systematic literature review aims to collate the available evidence on the following issues: patient demographics, aetiology, lesion location(s), malignant potential, location and histopathological features of transformed lesions, disease-specific survival rates and treatment response. Electronic databases were searched for studies in the English language reporting original data from at least 10 patients with PVL on the target issues of the present review. The retrieved data were merged and a descriptive analysis performed. The 20 studies selected indicated that PVL does not seem to be correlated with the major risk factors for oral carcinoma (tobacco, alcohol and/or areca nut/betel leaf chewing). The disorder affects mainly adult/elderly women and has a very high malignant transformation rate, particular site distribution and particular location and histopathological features of transformed lesions. The present results may be limited by some articles being unintentionally excluded as they were not found during the electronic search, a lack of worldwide accepted diagnostic criteria for PVL, and overlapping data from multiple studies performed in a limited number of centres. Despite these potential drawbacks, the present results demonstrate that PVL does have particular features.

Oral squamous cell carcinoma associated with proliferative verrucous leukoplakia compared with conventional squamous cell carcinoma--a clinical, histologic and immunohistochemical study

OBJECTIVE

Proliferative verrucous leukoplakia (PVL), a potentially malignant disorder, often undergoes malignant transformation to oral squamous cell carcinoma. The aim of our study was to document and compare the histologic, immunohistochemical, and clinical features and the survival rates of carcinoma arising in patients with PVL (p-scca) with conventional squamous cell carcinoma (c-scca) in order to determine if p-scca should be categorized as a separate clinical entity.

MATERIALS AND METHODS

A retrospective review of 11 patients with PVL, 38 with p-scca tumors and 49 with c-scca tumors: buccal mucosa (n = 28) and gingiva or palate (n = 21). Immunohistochemistry was performed by using antibodies directed against p16, p53, and ki67.

RESULTS

P-scca had lower clinical stage (P = .0001), smaller tumor size (P = .0033), no lymph node metastasis (P = .0002) or distant metastasis (P = .05), and better short term (P = .03), but not long term (P = .12) survival. Microscopically, p-scca tumor thickness was significantly less (P = .0001). P-53 overexpression was more common in p-scca (P = .0043) but not ki67 or p16 overexpression.

CONCLUSIONS

P-scca, compared with c-scca, presented with significantly better prognostic factors and short-term survival rates and longer duration of disease. Our results suggest that p-scca may represent a distinct entity, which may have practical implications when deciding on treatment. Further studies on a larger cohort of patients are recommended.

Retrospective case-control study of viral pathogen screening in proliferative verrucous leukoplakia lesions

OBJECTIVE

This study aimed to survey the presence of known oncoviruses in oral biopsies from patients diagnosed with the aetiologically undetermined proliferative verrucous leukoplakia and compare results to those from milder oral leukoplakia (OL) cases, oral squamous cell carcinoma, a common outcome of the lesions of interest, and healthy controls.

DESIGN

Blind, retrospective, case-control study.

SETTING

A stomatology unit in an academic Hospital and a Public Health laboratory.

PARTICIPANTS

Forty patients were divided in four groups. Ten patients had been diagnosed with proliferative verrucous leukoplakia, 10 with OL and 10 with OSCC, and 10 were healthy subjects.

MAIN OUTCOME MEASURES

The presence or absence of oncovirus DNA was assayed with the amplification of viral genetic markers using PCR and subsequent gel electrophoresis confirmation. Amplified fragments were sequenced and identified bioinformatically.

RESULTS

No DNA from the herpesvirus, papillomavirus or polyomavirus species was detected in the samples.

CONCLUSIONS

No association between proliferative verrucous leukoplakia and target viruses was detected. A higher throughput viral metagenomic approach may prove valuable for future analyses, as it would not be restricted to a priori knowledge of potential targets.

Proliferative verrucous leukoplakia: recognition and differentiation from conventional leukoplakia and mimics

The majority of conventional leukoplakia remains constant and only a subset progress to high-grade dysplasia or invasive carcinoma. A less recognized form known as proliferative verrucous leukoplakia (PVL) represents a unique progressive and elusive variant. Identifying patients with this form can only be achieved through the keen clinical observation of the temporal gross and histologic progression in individual patients with squamous cell carcinoma. The difficulty in the early diagnosis of PVL stems from the overlapping clinical and pathologic features with conventional multifocal leukoplakia with dysplasia. We present the current view on the clinicopathologic and biological characteristics of PVL and discuss their diagnosis, differential diagnosis, and management.

Proliferative verrucous leukoplakia: an elusive disorder

Proliferative Verrucous Leukoplakia (PVL) is a multifocal form of progressive leukoplakia with a high rate of malignant transformation that requires early recognition by oral health care providers for proper management.

BACKGROUND AND PURPOSE

PVL will frequently appear as an innocuous white lesion or lesions that can easily be overlooked or considered clinically insignificant, yet it has a high rate of malignant transformation. There is limited in-depth knowledge about the pathobiology of PVL. Oral health care providers lack familiarity with this lesion; consequently the intent of this article is to increase awareness of the clinical aspects of PVL.

METHODS

Case reports, case series and review articles provide a profile of PVL.

CONCLUSION

It is essential that health care providers performing intraoral examinations are aware that PVL is a distinct and rare form of multifocal oral leukoplakia. PVL commonly affects females above the age of 62. Currently, little is known about its etiopathogenesis. Additionally, no specific treatment modality has proven to be effective in aborting its progression. Because of its high recurrence potential and relentless progression to squamous cell carcinoma, all recurrent and multifocal white lesions of the oral cavity should be viewed with suspicion.

Urban legends series: oral leukoplakia

To date, the term oral leukoplakia (OL) should be used to recognize 'predominantly white plaques of questionable risk, having excluded (other) known diseases or disorders that carry no increased risk of cancer'. In this review, we addressed four controversial topics regarding oral leukoplakias (OLs): (i) Do tobacco and alcohol cause OLs?, (ii) What percentage of OLs transform into oral squamous cell carcinoma (OSCC)?, (iii) Can we distinguish between premalignant and innocent OLs?, and (iv) Is proliferative verrucous leukoplakia (PVL) a specific entity or just a form of multifocal leukoplakia? Results of extensive literature search suggest that (i) no definitive evidence for direct causal relationship between smoked tobacco and alcohol as causative factors of OLs, (ii and iii) the vast majority of OLs follow a benign course and do not progress into a cancer, and no widely accepted and/or validated clinical and/or biological factors can predict malignant transformation, and (iv) the distinction between multifocal/multiple leukoplakias and PVL in their early presentation is impossible; the temporal clinical progression and the high rate of recurrences and development of cancer of PVL are the most reliable features for diagnosis.

Human papillomavirus and oral disease - emerging evidence: a review

Human papillomavirus (HPV) infections have received considerable attention in recent years. Of the 120 or so known types of the virus, some cause a variety of benign wart-like lesions of the skin and genital and oral mucosae, whilst others are aetiologically associated with cervical and anogenital cancers. Recent epidemiologic evidence suggests that HPV may also be an independent risk factor for oropharyngeal cancer. In this context it has been suggested that HPV virus may modulate the process of carcinogenesis in some tobacco and alcohol induced oropharyngeal cancers and act as the primary oncogenic agent for inducing carcinogenesis among non-smokers. Dental practitioners have a major role in detecting all lesions of the oral mucosa caused, or possibly caused, by HPV. This paper briefly reviews the current state of knowledge of molecular and clinical aspects of HPV infections of the oral mucosa.

Human papillomaviruses in oral carcinoma and oral potentially malignant disorders: a systematic review

OBJECTIVES

Human papillomavirus (HPV) in oral carcinoma (OSCC) and potentially malignant disorders (OPMD) is controversial. The primary aim was to calculate pooled risk estimates for the association of HPV with OSCC and OPMD when compared with healthy oral mucosa as controls. We also examined the effects of sampling techniques on HPV detection rates.

METHODS

Systematic review was performed using PubMed (January 1966-September 2010) and EMBASE (January 1990-September 2010). Eligible studies included randomized controlled, cohort and cross-sectional studies. Pooled data were analysed by calculating odds ratios, using a random effects model. Risk of bias was based on characteristics of study group, appropriateness of the control group and prospective design.

RESULTS

Of the 1121 publications identified, 39 cross-sectional studies met the inclusion criteria. Collectively, 1885 cases and 2248 controls of OSCC and 956 cases and 675 controls of OPMD were available for analysis. Significant association was found between pooled HPV-DNA detection and OSCC (OR = 3.98; 95% CI: 2.62-6.02) and even for HPV16 only (OR = 3.86; 95% CI: 2.16-6.86). HPV was also associated with OPMD (OR = 3.87; 95% CI: 2.87-5.21). In a subgroup analysis of OPMD, HPV was also associated with oral leukoplakia (OR = 4.03; 95% CI: 2.34-6.92), oral lichen planus (OR = 5.12; 95% CI: 2.40-10.93), and epithelial dysplasia (OR = 5.10; 95% CI: 2.03-12.80).

CONCLUSIONS

The results suggest a potentially important causal association between HPV and OSCC and OPMD.

Contemporary concepts in the diagnosis of oral cancer and precancer

This article addresses several issues in the approach to diagnosis of oral cancer. The term oral cancer is clarified. Key aspects of the biologic basis of development of oral cancer and the known risk factors associated with the disease are summarized. The clinical presentation of oral cancers and precancerous lesions and their histopathologic correlates is discussed. The importance of conventional tissue biopsy as the prevailing gold standard for diagnosis is emphasized. Other current technologies available for detecting and diagnosing oral cancer and premalignant lesions are acknowledged, and their respective strengths and weaknesses are discussed.

Oral premalignant lesions: from a clinical perspective

In this review article, the clinical and histopathological characteristics of oral premalignant lesions, and primarily oral leukoplakia, are noted and the risk factors for malignant transformation of oral leukoplakia are discussed. Malignant transformation rates of oral leukoplakia range from 0.13 to 17.5%. The risk factors of malignant transformation in the buccal mucosa and labial commissure are male gender with chewing tobacco or smoking in some countries such as India, or older age and/or being a non-smoking female in other countries. Some authors have reported that leukoplakia on the tongue or the floor of the mouth showed a high risk of malignant transformation, although others have found no oral subsites at high risk. In concurrence with some authors, the authors of this review view epithelial dysplasia as an important risk factor in malignant transformation; however, there are conflicting reports in the literature. Many authors believe that nonhomogeneous leukoplakia is a high risk factor without exception, although different terms have been used to describe those conditions. The large size of lesions and widespread leukoplakia are also reported risk factors. According to some studies, surgical treatment decreased the rate of malignant transformation; however, many review articles state that no definitive treatment including surgery can decrease the malignant transformation rate of oral leukoplakia because of the lack of randomized control trials of treatment. Tobacco chewing and smoking may be causative agents for cancerization of oral leukoplakia in some groups, and evidence for a role of human papilloma virus in the malignant transformation of oral leukoplakia is inconsistent. Further research to clarify its role in malignant transformation is warranted.

Proliferative verrucous leukoplakia: a concise update

Proliferative verrucous leukoplakia (PVL) is of uncertain etiology but may be associated with human papillomavirus (HPV) infection. Proliferative verrucous leukoplakia is seen mainly in older women, beginning as a simple slow-growing, persistent leukoplakia that tends to spread and become multifocal and affect the gingival frequently. In time, PVL develops exophytic, wart-like or erythroplakic areas that become squamous carcinomas. Proliferative verrucous leukoplakia appears to resist to all attempts at therapy and often recurs.