Verrucous Keratoses Associated with Checkpoint Inhibitor Immunotherapy

Introduction: Checkpoint inhibitor immunotherapy is associated with numerous adverse events, including eruptive keratoacanthomas and squamous cell carcinomas. However, no cases of immunotherapy-associated verrucous keratoses (VKs) have been reported. VKs are proliferative lesions generally considered benign, although they have been suggested to represent premalignant lesions. Cases: We present the first case series of three patients with immunotherapy-associated VKs. The patients were receiving nivolumab for renal cell carcinoma, combination ipilimumab/nivolumab for non-small cell lung carcinoma, and pembrolizumab for malignant melanoma. The VKs appeared 3-7 months after initiation of immunotherapy. Lesions were treated with shave removal or cryosurgery without recurrence. This report adds to the spectrum of cutaneous squamoproliferative lesions induced by checkpoint inhibitor immunotherapy.