Drug-induced pemphigoid and linear IgA disease

Drug-induced pemphigoid (DIBP) and drug-induced linear IgA bullous dermatosis (DILAD) can be difficult to differentiate from idiopathic bullous pemphigoid (BP) or mucous membrane pemphigoid (MMP), respectively linear IgA disease (LAD). Possible absence or only minor differences in clinical, histopathologic and immunopathologic features complicate the recognition. However, differentiation can be of major importance because of a different approach, prognosis, and treatment. Diagnosis is mainly based on a clear time-relation between start of the suspected drug(s) and onset of the lesions, but can be complicated by polypharmacy and comorbidity, especially in the elderly. After withdrawal of the culprit drug, both DIBP and DILAD tend to be self-limiting. With the introduction of immune checkpoint inhibitors in treatment of malignancies, pemphigoid variants may present as an immune-related adverse event, leading to a dilemma in treatment choices.