LAUSR

BACKGROUND Cutaneous adverse effects of immunotherapies are being seen with increasing frequency in general practice. While anti-PD1 lichenoid reactions are well known, only a few cases of bullous lichen planus have so far been reported in the medical literature. Herein we described a case of secondary bullous lichen planus associated with nivolumab and we present a systematic review of all anti-P1-induced cases reported in the literature. PATIENTS AND METHODS Three months after beginning treatment with nivolumab for metastatic clear-cell renal carcinoma, a 68-year-old man presented pruritic purplish papules on his limbs that subsequently became bullous. Clinical-histological correlation led us to a diagnosis of secondary bullous lichen planus induced by nivolumab. Systemic steroids and withdrawal of immunotherapy resulted in clinical improvement. REVIEW OF THE LITERATURE Our systematic review revealed 20 cases of lichen planus induced by anti-PD1 (nivolumab and pembrolizumab) published between 2016 and 2018, 6 of which were of the bullous form. Treatment and maintenance or discontinuation of anti-PD1 were dependent on severity. DISCUSSION Bullous lichen planus has been reported only rarely in the context of nivolumab therapy. The timeline for development of cutaneous adverse reactions under anti-PD1 immunotherapy may last weeks or months and regular monitoring is required. Withdrawal of immunotherapy should only be considered where the outcome under systemic corticosteroids is unfavourable.