Background and aim: Oral lichen planus, is a chronic inflammatory mucocutanous lesion which is defined as a premalignant lesion. Matrix metaloprotenase 2 (MMP-2) and MMP-9 are protenases which facilitates invasion of tumoral cells to connective tissue and are over-expressed in premalignant and malignant lesions. The aim of this study was to determine the expression of MMP-2 in erosive and non-erosive oral lichen planus and inflammatory hyperplasia by immunohistochemistry.
Methods: in this cross sectional study 39 specimens of non-erosive oral lichen planus (with and without dysplasia), 36 specimens of erosive ones (11 dysplastic and 25 non-dysplastic, 32 inflammatory hyperplasias and 6 samples of normal oral mucosa were chosen form pathology archive of Faculty of Dentistry, Mashhad university of Medical Sciences and were stained immunohistochemically by MMP-2 and MMP-9 markers. Kruskal-Wallis, Mann-Whitney and Spearman correlation coefficient were used.
Results: The highest mean expression of MMP-2 and MMP-9 (in all layers) were observed in erosive oral lichen planus (68.18±31.62 and 94.5±3.5, respectively). MMP-9 expression in erosive oral lichen planus in comparison to non-erosive one showed significant difference in all layers (P<0.001) and the expression of MMP-2 showed a significant difference in basal –para basal and prickle layers (respectively: P=0.008, P<0.001).
Conclusion: the linear increase seen in the expression of markers from normal mucosa to erosive oral lichen planus indicates the difference of biological behavior between erosive and non-erosive oral lichen planus. Hence, it is concluded that erosive oral lichen planus is of the higher premalignan potential compared with its non-erosive correspondent.