Immune Checkpoint Inhibitor-Induced Psoriasiform, Spongiotic, and Lichenoid Dermatitis: A Novel Clinicopathological Pattern.

Immune checkpoint inhibitors (ICIs), a class of anticancer agents that upregulate T-cell response to tumor cells, are associated with immune-related adverse events (irAEs), and the skin is one of the most commonly affected organs. We report the first two cases of a unique ICI-induced clinicopathological entity. A psoriasiform-appearing eruption with psoriasiform, spongiotic, and lichenoid dermatitis pattern on histopathology. A 73-year-old male with stage IV melanoma treated with nivolumab and a 63-year-old female with stage IV colorectal cancer treated with pembrolizumab and TAK-981 separately presented to our clinic with a psoriasiform rash. In both patients, punch biopsy revealed an unusual combination of psoriasiform, spongiotic, and lichenoid dermatitis. Treatment with apremilast in the first patient yielded some improvement, while treatment with ixekizumab in the second patient yielded a complete resolution of the eruption. Our cases add to the growing body of reported immune toxicities related to ICI use and illustrate the utility of targeted immune suppression of pathways in disease phenotype to allow for ICI continuation and optimization of cancer treatment.