Squamous cell carcinoma in a patient with oral lichen planus treated with topical application of tacrolimus

Oral lichen planus (OLP) is a chronic mucosal disorder of unclear etiology. The mainstay of therapy is topical use of steroids but other immuno-modulating therapies have also been tried. One such example is topical application of tacrolimus. Tacrolimus was in 2000 approved for treatment of atopic dermatitis, but in 2005 a boxed warning was included because of a potential risk of cancer development and for lack of long-term studies of the safety of the drug. The present study describes a patient who in 2003 was diagnosed with OLP and where treatment has included an intermittent use of tacrolimus. Five years after diagnosis, the patient developed a squamous cell carcinoma in the region where tacrolimus had been applied. The possible relationship between the use of tacrolimus and cancer development and rationale to include tacrolimus in OLP treatment is discussed.