Keywords: BP, bullous pemphigoid; C3, complement component 3; DIF, direct immunofluorescence; ICI, immune checkpoint inhibitor; ICI-BP, immune checkpoint inhibitor–induced bullous pemphigoid; PV, pemphigus vulgaris; autoimmune disease; bullous pemphigoid; immune checkpoint inhibitor; immune checkpoint inhibitor–induced bullous pemphigoid; immune-related adverse event; radiation therapy.