Case report: a successful treatment with immune checkpoint inhibitors was associated with severe dermatologic toxicities in a patient with double primary malignancies.

Dermatological toxicities are well-recognized immune-related adverse events (irAEs) secondary to immune checkpoint inhibitor (ICI) use. Corticosteroids are considered the first-line therapy for grade 3 or grade 4 skin irAEs, but long-term usage of corticosteroids may abolish the effect of ICIs. Multiple antitumor therapies might be an influencing factor in an increased incidence of skin irAEs. The safety and prognostic value in resuming ICIs after irAEs has been inconsistently reported, especially the severe skin irAE. We report a case of a 75-year-old man with non-small cell lung cancer (NSCLC) and prostate cancer with a Stevens-Johnson syndrome (SJS)-like eruption. The severe rash might have been induced by resuming pembrolizumab was successfully treated with a combination of corticosteroids, gamma globulin, and immunosuppressants. Early detection of dermatologic toxicity is crucial, especially for patients receiving multiple antitumor treatments. We should treat ICI resumption seriously after skin irAE.