Bullous pemphigoid and the pembrolizumab conundrum

Pembrolizumab is an immune checkpoint inhibitor that is gaining widespread use as an immunotherapy for various cancers. With its growing application, a range of immune-related adverse events are being more frequently recognized. Pruritus, lichenoid reaction and eczema are known dermatological adverse effects of pembrolizumab, but bullous pemphigoid (BP) is a rare adverse effect of the drug. We present the case of a 59-year-old male who developed BP after being treated with pembrolizumab for renal cell carcinoma. It has been established that triggering of BP with programmed cell death protein-1 inhibitors like pembrolizumab correlates well with tumor suppression. Hence, there is a line of thought that programmed cell death protein-1 inhibitors may be continued and BP be managed with immunomodulatory therapy. Our patient responded well to monthly intravenous immunoglobulin injections while continuing pembrolizumab.