Lichen planus-like eruptions: An emerging side effect of tumor necrosis factor-α antagonists

As tumor necrosis factor (TNF)-alpha inhibitors gain wider use in clinical practice, it is becoming increasingly evident that these potent immunosuppressants can also induce inflammatory reactions. We present two cases of lichen planus-like eruptions after infliximab and adalimumab therapy for psoriasis, and review the literature on this phenomenon. Eleven cases of lichen planus or lichenoid drug eruptions have been previously reported in patients taking TNF-alpha inhibitors, in addition to several cases of psoriasiform eruptions With a lichenoid histology. Because TNF-alpha has been implicated in the pathogenesis of lichen planus, induction of lichenoid reactions by TNF-alpha inhibition is somewhat unexpected. We consider potential immunologic mechanisms, and suggest that TNF-alpha inhibition may precipitate lichenoid reactions through disruption of a delicate balance between TNF-alpha and interferon-a in susceptible patients. (J Am Acad Dermatol 2009;61:104-11.)