A Case of Systemic Severe Bullous Pemphigoid Caused by Long-Term Sintilimab Treatment for Renal Cell Carcinoma

Immune-related adverse events have been reported in relation to programmed cell death protein-1 (PD-1). However, there are few reports on PD-1 inhibitor-induced bullous pemphigoid. We report the case of a patient who developed bullous pemphigoid following long-term administration of sintilimab for renal cell carcinoma. He developed scattered erythema, blisters, and generalized pruritus for 1 week before admission. Histopathology showed subepidermal blisters and direct immunofluorescence showed linear deposition of immunoglobulin G and complement 3 on the basement membrane; the level of BP180 was 146.93U/mL. A regimen containing methylprednisolone, minocycline, and niacinamide was administered and the patient was discharged following resolution of symptoms.