INTRODUCTION
Immune checkpoint inhibitors including programmed death protein 1 (PD-1) inhibitors show great therapeutic benefit for numerous advanced malignancies, but cause a spectrum of immune-related adverse events (irAEs), with cutaneous toxicity being a common presentation.1,2 Cutaneous irAEs present with variable onset and severity,2 ranging from a self-limiting maculopapular rash to life-threatening Steven-Johnson’s syndrome (SJS)/toxic epidermal necrolysis (TEN) requiring inpatient management.1 Updated guidelines for management of irAE were compiled by the American Society of Clinical Oncology (ASCO) based on expert consensus, with recommendations for both bullous dermatoses and severe cutaneous adverse reactions (SCARs).3 We report two cases of pembrolizumab causing grade 3 bullous lichenoid dermatitis involving >50% total body surface area (TBSA) successfully treated in the outpatient setting with oral dexamethasone and minimal to no interruption of PD-1 inhibitor therapy.
CASE 1
A 72-year-old male with stage IV adenocarcinoma of the lung diagnosed 2 months prior presented with an erythematous, pruritic rash for 3 weeks. This occurred after 2 cycles of carboplatin, pemetrexed, and pembrolizumab. Physical examination demonstrated confluent erythematous plaques involving the trunk and arms (Figure 1A). He was treated with topical corticosteroids, but the eruption flared upon pausing treatment. Punch biopsy of the right chest demonstrated interface dermatitis with epidermal necrosis, including epidermal dysmaturation, scattered dyskeratosis, and superficial perivascular infiltrate of lymphocytes and occasional neutrophils. Immunohistochemistry demonstrated non-specific
