Regression of cutaneous squamous cell carcinoma after the development of pembrolizumab‐induced bullous pemphigoid

Abstract

Abstract Bullous pemphigoid is a rare complication of immune checkpoint inhibitor treatment. We report a case of pembrolizumab‐induced bullous pemphigoid in a patient with malignant melanoma and concomitant cutaneous squamous cell carcinoma that regressed. A 77‐year‐old woman with metastatic malignant melanoma and a 3‐year history of a growing skin nodule on her left calf was treated with pembrolizumab. Histopathological examination of the skin nodule established the diagnosis of cutaneous squamous cell carcinoma. Seven months after the initiation of pembrolizumab treatment, the patient developed bullous pemphigoid. Discontinuation of pembrolizumab and initiation of oral prednisolone resulted in the resolution of the skin blisters. Additionally, complete response of the metastatic malignant melanoma was noted after pembrolizumab treatment. Furthermore, the cutaneous squamous cell carcinoma completely resolved after the development of bullous pemphigoid. This case supports the hypothesis that the development of bullous pemphigoid is indicative of a sufficient antitumor response after immunotherapy.

Keywords

• bullous pemphigoid
• immune checkpoint inhibitor
• pembrolizumab
• skin
• treatment