Late presentation of generalised bullous pemphigoid‐like reaction in a patient treated with pembrolizumab for metastatic melanoma

Dermatological toxicity is one of the most commonly reported immune‐related adverse events in patients receiving checkpoint inhibitor immunotherapy. We report the gradual development of a widespread bullous pemphigoid‐like reaction in a metastatic melanoma patient 8 months after commencing treatment with the programmed‐death‐1 (PD‐1) inhibitor pembrolizumab, requiring prolonged corticosteroid therapy. This case highlights the potential for insidious and late development of severe cutaneous toxicity following PD‐1 inhibitor therapy and suggests that even prolonged immunosuppression may not necessarily compromise the efficacy of PD‐1 inhibition in advanced melanoma.