Premalignant nature of oral and vulval lichen planus: facts and controversies.

Although many classifications include oral lesions of lichen planus in the category of a premalignant condition, there is still much discussion about whether the mucous membranes lesions should be characterized as an intrinsically premalignant condition or merely as a facilitator of the action of a carcinogenic factor. The possibility that an epidermoid carcinoma can emerge at the site of lichen planus lesions, mainly in mucous membranes, has been shown; however, several published cases omit information about other potential risk factors. This prevents a complete analysis of the triggering relationship between lichen planus and squamous cell carcinoma. This contribution reviews the literature on this subject. The question of whether oral or vulval lichen planus, or both, are premalignant conditions will only be answered after prospective studies with large samples and extensive follow-up are performed, taking into consideration the great variety of risk factors involved, together with the establishment of a consensus in relation to the points still without agreement.