Malignant transformation of oral lichen planus: where are we now?

Oral lichen planus (OLP) is a very prevalent disease whose main clinical feature is the appearance of white hyperkeratotic reticular lesions, which may or may not be accompanied by erosive and/or atrophic lesions, among others. One of the most relevant aspects of the process is its current consideration as an oral potentially malignant disorder (OPMD), although this is currently the subject of considerable controversy.

A review of the literature was carried out in order to critically analyze the controversies surrounding the consideration of OLP as an OPMD, where they originate from and the available evidence that has led to the conclusion that OLP patients are at risk of developing oral cancer.

The controversies over the definitive acceptance of OLP as an OPMD were classified as controversies related to the lack of widely accepted diagnostic criteria for OLP; controversies related to histopathological aspects of OLP and the presence of epithelial dysplasia as a diagnostic exclusion criterion; and controversies related to clinical aspects of OLP (which in turn were subclassified into: controversies on how to interpret reticular lesions in OLP, on the nature of the white plaques that appear in OLP; on the changing character of reticular lesions in OLP; and on the criteria for accepting a case as a true malignant OLP). Furthermore, evidence to justify the acceptance of OLP as an OPMD was in depth reviewed, including the molecular evidence, evidence from research studies with the highest evidence design -systematic reviews and meta-analyses-, and evidence from case series reporting strong results.

This paper presents the reasons for the controversies as well as the evidence that allows us to accept that OLP behaves as an OPMD.