PD-1 inhibitors induced bullous lichen planus-like reactions: a rare presentation and report of three cases.

The introduction of immunotherapy such as antiprogrammed death1 (anti-PD1) monoclonal antibodies has changed the scenario of treatment in cancer. Apart from their impressive efficacy profiles, they are better tolerated than the anticytotoxic T-lymphocyte-associated protein 4 antibodies. Dermatological adverse events such as pruritus and rash have been reported in various clinical trials. We report three cases of anti-PD1-induced bullous lichen planus (LP)-like reactions encountered in our institution. These patients developed LP-like papules and annular plaques with vesicles or crusted centres. Histology showed LP-like changes with negative immunofluorescence. Vesiculobullous lesions in patients treated with anti-PD1 therapies require a careful clinicopathological evaluation.