Nivolumab induced inflammation of seborrheic keratoses: a novel cutaneous manifestation in a metastatic melanoma patient

Immune checkpoint inhibitors targeting the programmed cell death (PD)-1 receptor have dramatically changed the landscape of metastatic melanoma treatment. Nevertheless, these immuno-modulatory agents have associated side effects, including dermatologic manifestations. To this end, we report a patient with metastatic melanoma that was treated with PD-1 inhibitor, and subsequently developed inflammation of existing seborrheic keratosis lesions and new verrucous keratoses, a cutaneous side effect that has not been previously reported to our knowledge. The etiology of seborrheic and verrucous keratoses is not well understood, although their physical and histopathologic similarities to chronic viral-derived lesions, such as human papilloma virus, suggest a potential viral association. Chronic viral infections are known to result in T-cell tolerance because of persistent antigen stimulation. PD-1 inhibition is able to reinvigorate exhausted T cells, which are accordingly able to decrease viral load. Thus, the inflammatory reaction, seen in our patient, may be the result of PD-1 inhibition reactivating virally driven T lymphocytes. Correspondence to Joshua Arbesman, MD, Department of Dermatology, Case Western Reserve University, 2109 Adelbert Road, Cleveland, OH 44106, USA Tel: +1 216 368 6085; fax: +1 216 844 8993; e-mail: jxa248@case.edu Received February 23, 2018 Accepted May 30, 2018 Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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