A 68-year-old man is brought to the clinic by his wife due to new-onset pruritic skin lesions. Yesterday, while gardening, he developed generalized itching, and this morning he awoke with multiple intensely pruritic blisters. Application of calamine lotion provided no relief. His medical history includes early dementia, asthma, hypertension, and inflammatory bowel disease. Current medications are aspirin and lisinopril. Vital signs are within normal limits. Physical examination reveals multiple tense bullae and areas of excoriation on the arms. A punch biopsy of a lesion is obtained, and direct immunofluorescence microscopy is shown in Figure A. Which of the following is associated with this patient’s most likely diagnosis?