Severe psoriasis as an immune-related adverse event after long-term atezolizumab therapy for pulmonary large-cell neuroendocrine carcinoma: A case report.

Immune checkpoint inhibitors, such as atezolizumab, have become integral to the treatment of various malignancies and have significantly improved clinical outcomes by enhancing host antitumor immune responses. However, with their expanding clinical use, immune-related adverse events (irAEs) have been increasingly recognized. These events may involve any organ system and pose new challenges in patient management. Most irAEs occur within the first few months following treatment initiation; however, they may also develop unexpectedly after prolonged periods of stable therapy. Late-onset irAEs are generally mild to moderate in severity, although a subset can progress to severe forms. Dermatological toxicities are the most frequently observed irAEs. Although most cutaneous reactions are mild and manageable, severe skin toxicities, although relatively uncommon, can substantially impair patients' quality of life and may necessitate treatment modification or discontinuation. Psoriasis is a recognized cutaneous irAE that may present either as a de novo disease in patients without a history of psoriasis or as an exacerbation of pre-existing psoriasis. This case report describes a rare presentation of severe psoriasis that developed following long-term atezolizumab therapy and improved following treatment with oral prednisolone in 61-year-old man with pulmonary large-cell neuroendocrine carcinoma.