Pembrolizumab-induced hypertrophic lichenoid dermatitis with involvement of an old tattoo

We present the case of a 58-year-old man who developed hypertrophic lichenoid dermatitis secondary to pembrolizumab, with involvement of normal skin as well as the red-ink areas of an old tattoo site. Lichenoid dermatitis is a well-recognized immune-related adverse event to immune checkpoint inhibitors, but the hypertrophic variant secondary to pembrolizumab has been reported infrequently in the literature. Successful management of the cutaneous eruption in this case enabled the patient to resume life-prolonging adjuvant immunotherapy for clear-cell renal-cell carcinoma.