Pembrolizumab-Induced Rupioid Psoriasis Treated by Apremilast Without Interrupting the Ongoing Antineoplastic Treatment.

We report the case of a 77-year-old man affected by a poorly differentiated metastatic pulmonary adenocarcinoma who, after the first course of therapy with cisplatin-pemetrexed-pembrolizumab treatment, developed rupioid psoriasis. We decided to discontinue pembrolizumab for four weeks until lesions improved and to start therapy with apremilast (an oral small molecule phosphodiesterase (PDE)4 inhibitor) in combination with systemic methylprednisolone 16 mg/day with consequent tapering until discontinuation in a few weeks. After accomplishing three months of treatment with apremilast, the patient gained complete remission of the rupioid lesions. Pembrolizumab therapy was reintroduced, and cycles were carried out without exacerbating the clinical picture. During the fourth month of therapy with apremilast, it was attempted to stop the treatment despite continuing the therapy with pembrolizumab. As a result, there was a relapse of the erythematous scaling plaques. After the subsequent reintroduction of apremilast, a new remission of the clinical picture occurred despite the absence of interruption of pembrolizumab. As far as we know, this is the second case of rupioid psoriasis induced by immunotherapy with pembrolizumab. Still, while the previous case was undergoing therapy with acitretin and methylprednisone, our patient is the first case treated with apremilast with excellent and rapid remission even after discontinuation and re-administration of pembrolizumab without exacerbation of dermatitis. In addition, the appearance of psoriasis during immunotherapy can be properly treated, which does not contraindicate the continuation of the antineoplastic treatment.