Lichen planus pemphigoides induced by anti-PD-1 antibody: A case only involved in oral mucosa with excellent topical treatment efficiency.

Lichen planus pemphigoides (LPP) is a rare autoimmune subepidermal disease that can occur in patients receiving immune checkpoint inhibitors. Its clinical manifestations are combined with the characteristics of lichen planus with bullous pemphigoid that can occur on either skin or oral mucosa. It should be noted that oral LPP is very rare. Here, we report a novel case of oral LPP induced by an anti-PD-1 agent. The patient presented with typical clinical features in oral mucosa, and the diagnosis was based on histopathology and immunological studies. Given that the patient was receiving an anti-PD-1 agent, topical therapy was chosen, and a nice therapeutic effect was obtained. No significant recurrence was observed after a 2-year follow-up. A good and stable therapeutic effect achieved by rapid and local symptomatic medication suggests that accurate and sensitive diagnosis is necessary.