De Novo Psoriasis Vulgaris Diagnosed after Nivolumab Treatment for Refractory Hodgkin's Lymphoma, Completely Resolved after Autologous Hematopoietic Stem Cell Transplantation.

The programmed cell death protein-1 (PD-1) inhibitor nivolumab has been recently approved as an effective and safe treatment for patients with refractory/relapsed Hodgkin's lymphomas. Dermatological adverse events, mainly skin rash, have been reported in 1-5% of patients. We describe a case of de novo psoriasis vulgaris (PsV), diagnosed after nivolumab treatment for refractory Hodgkin's lymphoma. After administration of 6 cycles, skin lesions appeared in the right tibia, forearms, and dorsum of hands, and biopsy confirmed the diagnosis of PsV. The lesions completely resolved after autologous stem cell transplantation (ASCT) which was performed in the context of the treatment for the primary disease. PsV is an inflammatory skin disease, and it is considered to be mediated through cytotoxic T-cells. PD-1 blockage may lead to expansion of such T-cells, resulting thus in PsV appearance. The early published studies showed that nivolumab represents a safe treatment approach. PsV occurrence has not been reported so far in patients treated with nivolumab for hematological diseases, and it seems that long-term follow-up is necessary to fully clarify the entirety of PD-1 inhibitors' skin adverse events. Additionally, this clinical observation provides an evidence for a potential exploitation of ASCT in refractory and severe forms of PsV.