Chemical burn from topical apple cider vinegar

To the Editor: Chemical burns are often associated with strong acids such as sulfuric, nitric, and hydrochloric acids, but can occur with weaker acids such as acetic acid.1 An 8-year-old boy with a history of Crohn’s disease and HLA-B27-positive spondyloarthropathy had developed multiple lesions of mollusca contagiosa on his left leg over several weeks. His medications were weekly methotrexate (15 mg for the past year) and more recently, 3 doses of adalimumab (40 mg every other week). The evening before presentation, in an attempt to treat the mollusca contagiosa, his mother applied cotton balls soaked in apple cider vinegar (∼5% acetic acid) to the left popliteal fossa and side of his left knee.