Ibrutinib and other BTK inhibitors are also known to cause various cutaneous manifestations, including cellulitis, neutrophilic dermatoses, ecthyma, lichenoid eruption, onychomadesis, paronychia, pyogenic granuloma (periungual), pityriasis rosacea, and pyoderma gangrenosum. This evidence concerns the gene BTK and pyoderma gangrenosum.