Track: Case Reports

Topic: Inflammatory Diseases

Abstract:

A 65-year-old female with stage III invasive ductal carcinoma presented with a 4-month history of a blistering skin eruption, which started 1 week after her last dose of pembrolizumab (PD-1 inhibitor). Examination revealed erythematous to violaceous, annular plaques with central erosions on the trunk and extremities as well as scaly flat-topped papules on the hands and feet. Biopsy revealed a lichenoid infiltrate with eosinophils and sawtoothed epidermal rete with a broad subepidermal cleft. Direct immunofluorescence demonstrated linear IgG and C3 along the basement membrane. These findings were most consistent with a lichen-planus-pemphigoides (LPP)-like reaction to PD-1 checkpoint inhibition. Immunotherapy agents, while critical in the recent landscape of anticancer therapy, are associated with immune-related cutaneous adverse events. Lichenoid eruptions are among the most prevalent. Lichen planus-pemphigoides represents an uncommon immunobullous disorder in which lichenoid papules appear with bullae that can develop within the lichenoid lesion or, more typically, on uninvolved skin. Diagnosis may be challenging as histologic evaluation can be indistinguishable from bullous lichen planus or bullous pemphigoid. LPP usually reveals linear IgG or C3 deposition along the basement membrane on both DIF and IIF. The immunofluorescent findings in other lichenoid drug eruptions have not been consistently well described. In severe cases, immunotherapy is discontinued, and patients are treated most often with oral corticosteroids. However, there is some data suggesting that a lichenoid dermatitis in this setting may indicate a robust immune response and signal improved oncologic outcomes. Therefore, staying on treatment in milder cases may alter prognosis and patient survival.

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Aaron Fong, MD