Neutrophilic dermatoses as adverse effects of checkpoint inhibitors: A review.

Checkpoint inhibitors are a new class of drugs that enhance the immune system's intrinsic ability to destroy tumor cells by blocking signaling through the programmed cell death (PD-1) receptor, its ligand (PD-L1), and the cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4). The resulting increase in immunologic activity is responsible for a variety of adverse cutaneous reactions, which sometimes include neutrophilic dermatoses. We queried the PubMed database for existing cases of checkpoint inhibitors causing neutrophilic dermatoses. The literature search identified four cases of Sweet syndrome, four cases of pustular eruptions, two cases of pyoderma gangrenosum, and one case of bullous lupus erythematosus secondary to checkpoint inhibitors. All neutrophilic dermatoses were treated with topical or systemic steroids and most (9 of 11) completely resolved. Dermatologists should be aware of these rare, adverse cutaneous reactions to checkpoint inhibitors and how to approach their treatment, especially as their use increases.