Human papillomavirus and leukoplakia of the oral cavity: a systematic review

Introduction
Human papillomavirus (HPV) infection is mainly a problem of the female reproductive tract. It can occur in the oral cavity as well. Commonly HPV infections are subclinical, without any visible symptoms, and last no longer than 2 years. Usually the clinical manifestation of HPV infection is benign, but in some cases it can also promote malignant transformation. In the paper we have tried to estimate the prevalence of HPV detected in samples of oral leukoplakia (OLK), the most common premalignant lesions of the oral mucosa.

Aim
To review the current literature to estimate the prevalence of HPV (HPV DNA) detected in samples of oral leukoplakia.

Material and methods
We searched PubMed/Medline, Scopus, and Cochrane Library databases for studies that examined the prevalence of HPV in leukoplakia with HPV DNA detection by polymerase chain reaction.

Results
HPV positive cases in OLK ranged from 0% to 100% in studies. The overall HPV prevalence in leukoplakia was 6.66%. The prevalence of HPV 16 positive cases was 2.95%. The high-risk HPV prevalence was 5.16%, when the low-risk HPV prevalence was 3.32%. When dysplasia is mentioned, HPV was detected in 25.93% of lesions with dysplasia, compared to 37.14% among non-dysplastic lesions.

Conclusions
Further studies should be extended also to include low-risk HPV and compare its prevalence with presence of dysplasia in leukoplakia. Besides, leukoplakia and other premalignant lesions can no longer be treated as one lesion.