Several lines of evidence suggest that TNF-alpha plays a role in the pathogenesis of lichen planus. It has been shown that there are increased levels of TNF-alpha in the serum of these patients. In addition, skin and mucosal biopsies show increased TNF-alpha produced by the infiltrating lymphocytes as well as the basal keratinocytes. It has been suggested that the expression of TNF-alpha receptor on the basal keratinocytes may contribute to apoptosis. Also, TNFR1 (a TNF-alpha receptor) is expressed by the infiltrating mononuclear cells as well as the keratinocytes. Increased levels of soluble TNF receptors are also found in the serum of patients with lichen planus. A recent report also has shown that polymorphisms in the TNF-alpha gene are associated with both oral and cutaneous lichen planus. Finally, thalidomide, which partly functions as a potent inhibitor of TNF-alpha transcription, has been shown to be effective (in small case series and reports) in selected patients for the treatment of oral and genital lichen planus. However, thalidomide is a potent teratogen and cannot be used in women of childbearing potential. In addition, thalidomide usage not uncommonly results in neurotoxicity, which can be permanent, and thus limits use of this drug. Despite the evidence for a role of TNF-alpha in LP there are no reports of any TNF inhibitors being used for this disease.