Severe de-novo palmoplantar and nail psoriasis complicating Nivolumab treatment for metastatic melanoma.

Nivolumab, a fully human IgG4 immune checkpoint modulator, binds to the programmed cell death 1 (PD-1) receptor on T cells and blocks their inhibition. Thus, it increases the anticancer host immune response by allowing T cells to attack tumor cells. Although anti-PD-1 immunotherapy is typically well accepted, deregulation of immune tolerance caused by nivolumab may determine immune-related adverse events, among which skin toxicities represent the most common. We report a case of severe new-onset palmoplantar and nail psoriasis after receiving nivolumab treatment for metastatic melanoma.