In this study, we demonstrated that (1) incidence of DIIP by anti-IL-17/23 biologics was approximately 1.0% (6/603), (2) Age, baseline KL-6 level and underlying IP could be risk factors, (3) DIIP by anti-IL-17/23 biologics was mild, and developed at mean 14 months after initiation of the therapy (4) Serum KL-6 levels and chest CT were useful for not only predicting but also detecting DIIP. This evidence concerns the gene IL17A and incontinentia pigmenti.