A Case of Nivolumab-Induced Bullous Pemphigoid in a Patient with Metastatic Breast Cancer

Nivolumab is a checkpoint inhibitor monoclonal antibody, designed to interact with the programmed death cell receptor-1, preventing the inhibitory signaling on cytotoxic T cells. Immune checkpoint inhibitors can lead to severe cutaneous immune-related adverse events (irAEs). A 54-year-old female with a breast cancer metastasis was referred to our clinic due to diffuse cutaneous lesions of crusted erythematous patches and multiple blisters for 2 weeks. Five months before presentation, she started nivolumab/eribulin immunotherapy. Skin biopsy showed subepidermal blistering with perivascular lymphohistiocytic infiltration with eosinophils. Direct immunofluorescence showed linear deposition of immunoglobulin G and C3 along the dermoepidermal junction, consistent with bullous pemphigoid. Temporal relationship between initiation of nivolumab and skin lesion suggested the diagnosis of nivolumab-induced bullous pemphigoid. Dermatologic toxicity is the most common irAEs associated with nivolumab, but nivolumab-induced bullous pemphigoid is rare. Given the widespread use of immunotherapy, it is important to document this case to develop proper management strategies.