Oral lichenoid disease as a premalignant condition: the controversies and the unknown.

We grouped as oral lichenoid disease (OLD) a series of chronic inflammatory processes with autoimmune base that affect the epithelium of the oral mucosa. This disease presents in 2% of the population with a marked predilection for the female gender, especially perimenopausal women. Clinically, it is characterized by the presence of lineal reticular papules and histologically by liquefaction degeneration of the basal layer of the epithelium associated with an inflammatory infiltrate with a "band-like" disposition on the lamina propria, composed primarily of T lymphocyte cells. Its pathogenicity is associated with deregulation of the cellular immune system, where the activated cytotoxic CD8 and the CD4 T helper lymphocytes induce apoptosis of the epithelial cells. Classically it has been considered a precancerous condition, although the malignant transformation does not exceed 1% of cases. In recent years the differentiation between oral lichen planus (OLP) and oral lichenoid lesions (OLL) has become important, since the latter might have a greater malignant potential. In this paper, we analyse and update some controversial aspects of this frequent oral disease in relation to the diagnosis and malignant potential.