False‐negative direct immunofluorescence testing in vancomycin‐induced linear IgA bullous dermatosis: a diagnostic pitfall

To the Editor , Linear IgA bullous dermatosis (LAD) is an acquired immunobullous dermatosis that relies on direct immunofluorescence (DIF) testing showing linear deposition of immunoglobulin IgA along the basement membrane of the epidermis for diagnosis1. We present a case that highlights the utility of repeating the DIF testing when initial immunofluorescence findings do not support the clinical findings of drug-induced LAD or contradict the histopathologic findings in routinely stained sections. A 74-year-old African-American female with renal insufficiency and a stage four sacral