Pityriasis rubra pilaris-like erythroderma secondary to phosphoinositide 3-kinase inhibition

Background: Phosphoinositide 3-kinase (PI3K) inhibitors are a class of small-molecule inhibitors approved for the treatment of certain leukaemias and lymphomas. Their dermatological adverse event profile is poorly described. Aim: To characterize a rare cutaneous adverse event from PI3K inhibitors in order to help dermatologists and oncologists identify and effectively manage such eruptions. Methods: This was a retrospective analysis of patients receiving PI3K inhibitors referred to the Skin Toxicities Program in The Center for Cutaneous Oncology. Results: Three patients on PI3K inhibitors for treatment of malignancy developed diffuse erythroderma and keratoderma. Clinical and histopathological findings were consistent with pityriasis rubra pilaris (PRP)-like reactions. All patients improved with topical and oral corticosteroids, oral acitretin, and drug discontinuation. Conclusions: PRP-like cutaneous eruptions may develop secondary to PI3K inhibition. Early dermatological evaluation of cutaneous toxicities to PI3K inhibitors as well as rapid initiation of disease-specific treatments may help keep patients on life-prolonging anti-cancer therapies.