Resolution of pembrolizumab-associated lichenoid dermatitis with a single dose of methotrexate.

We present a 53-year-old woman with severe lichenoid dermatitis secondary to pembrolizumab therapy that was refractory to both topical and oral steroids. After almost three months without improvement, the rash was effectively combated with a single 15mg dose of methotrexate. We hope this case will help guide the management of the cutaneous adverse effects of anti-PD1 immunotherapy.