De novo subacute cutaneous lupus erythematosus-like eruptions in the setting of programmed death-1 or programmed death ligand-1 inhibitor therapy: clinicopathological correlation.

Immune checkpoint inhibitors (ICI) may cause eruptions resembling cutaneous autoimmune diseases. There are six cases of immunotherapy-associated subacute cutaneous lupus erythematosus (SCLE) in the literature. We present details of five patients referred to the Skin Toxicity Program at the Dana-Farber Cancer Institute/Brigham and Women's Cancer Center who developed de novo immunotherapy-associated SCLE-like eruptions, along with clinicopathological correlation and highlight potential mechanistic features and important diagnostic points. Two patients were maintained on topical corticosteroids, antihistamines and photoprotection. One had complete clearance and two had improvement with addition of hydroxychloroquine. Four patients continued their immunotherapy uninterrupted, while one had immunotherapy suspended for a month before restarting at full dose. Histopathologically, this series illustrates the temporal evolution of ICI-induced immune cutaneous reactions with SCLE subtype. Looking beyond the universally present lichenoid infiltrate, features of evolving SCLE were evident. We hypothesize that programmed death-1 blockade may induce immunological recognition of previously immunologically tolerated drug antigens, leading to epitope spreading and the SCLE phenotype.