Oral Lichen Planus and Oral Lichenoid Reaction--an Update.

Oral lichen planus (OLP) and oral lichenoid reaction (OLR) are clinically and histopathologically similar diseases. Whereas OLP is a consequence of T cell mediated autoinflammatory process to a still unknown antigen, OLR might be caused by drugs, dental restorative materials and dental plaque. Pubmed was searched and 24 publications published over the last three years regarding etiology, diagnosis and malignant alteration were included in this study. Patients with OLR who have amalgam fillings near lesions should have them replaced, i.e. when possible they should be referred to patch test, as well as when drug-induced OLR are suspected. OLR lesions induced by drugs should disappear when the offending drug has been discontinued. Histology finding in OLR consists of more eosinophils, plasma cells and granulocytes in comparison to OLP lesions. Furthermore, OLP lesions showed more p53, bcl-2 and COX-2 positivity when compared to OLR. OLP is characterized by infiltration, atrophic epithelium, rete pegs and Max Joseph spaces, while deep infiltration into connective tissue and hyperkeratosis were the criteria for making the diagnosis of OLR. The number of degranulated mastocytes in the reticular layer, as well as the number of capillaries was higher in OLR in comparison to OLP. It seems that OLR are more prone to malignant alteration in comparison to OLP.