Pembrolizumab-associated pyoderma gangrenosum in a patient with metastatic squamous cell carcinoma.

Pyoderma gangrenosum (PG) is a rare, ulcerative neutrophilic dermatosis that has been reported in association with certain medications. Recognition of medications that trigger PG may help to better understand the pathogenesis of the condition and to provide earlier diagnosis and treatment for affected patients. Herein, we report a case of new-onset PG following initiation of the checkpoint inhibitor pembrolizumab for the treatment of metastatic cutaneous squamous cell carcinoma. Our case was resistant to intralesional corticosteroid therapy, but ultimately improved with systemic corticosteroids and cessation of pembrolizumab.