Abstract: 【Abstract】 Case 1, a 63-year-old female patient presented with blisters and bullae arising in erythema all over the body with itching for 2 months. Two years ago, the patient underwent peri-intestinal lymph node dissection for the treatment of malignant melanoma of the rectum and anal canal, and received intravenous injection of toripalimab for preventive treatment for 1 year, and generalized skin lesions occurred 2 weeks after drug withdrawal. Direct immunofluorescence testing of erythema on the upper extremities showed that immunoglobulin G （IgG） was deposited along the basement membrane zone; salt-split indirect immunofluorescence testing of a serum sample showed liner deposition of IgG in the epidermis. Enzyme-linked immunosorbent assay （ELISA） revealed that the serum level of anti-BP180 antibodies was over 200 U/ml. The patient was diagnosed with bullous pemphigoid, but it was doubtful whether the disease was caused by PD-1 inhibitor toripalimab or not. Then, the patient received oral minocycline at a dose of 200 mg/d and prednisolone acetate at a dose of 20 mg/d, and topically applied halometasone cream all over the body. After half-a-month treatment, the blisters crusted over and the erythema darkened in color. Case 2, a 36-year-old female patient presented with generalized blisters and itching for more than 3 months. The skin lesions manifested as tense blisters, bullae, bloody bullae and crusts on the edematous erythema. The patient had a 3-year history of vaginal malignant melanoma, which was stage Ⅳ postoperative melanoma with local recurrence and lymph node metastasis nearby the right iliac vessels. After 2-year treatment with intravenous injection of toripalimab, generalized skin lesions occurred all over the body. Direct immunofluorescence testing of the erythema showed weakly positive staining for IgG, and linear deposition of IgG along the basement membrane zone; salt-split indirect immunofluorescence testing of a serum sample showed liner deposition of IgG in the epidermis. ELISA revealed that the serum level of anti-BP180 antibodies was over 200 U/ml. The case 2 was diagnosed with bullous pemphigoid, but it was also doubtful whether the disease was caused by PD-1 inhibitor toripalimab or not. Then, the case 2 was treated with oral doxycycline at a dose of 200 mg/d and oral prednisolone acetate at a dose of 40 mg/d. After 2-week treatment, the blisters completely crusted over and erythema darkened in color.

Key words: Pemphigoid, bullous, Programmed cell death 1 receptor, Antigens, CD274, Melanoma, Immune-related adverse event