Antibody drug conjugates (ADCs) represent a novel class of agents that directly target tumor cells for specific delivery of cytotoxic therapy. This selectivity allows for increased efficacy while reducing the potential for toxic effects.1,2 Loncastuximab tesirine (LT) is an ADC comprising a humanized anti-CD19 monoclonal antibody conjugated to a pyrrolobenzodiazepine dimer toxin through a cathepsin-cleavable valine-alanine linker.2,3 Loncastuximab tesirine has received accelerated US Food and Drug Administration approval for treating adult patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) after treatment with 2 prior lines of therapy.4 In this article, we describe 2 patients who presented with similar vesicular lesions during treatment with LT.