A drug rash that can mimic the very cancer the drug treats

Abstract

Abstract Linked Article: Trum et al. Br J Dermatol 2022; 186:153–166. Cutaneous T-cell lymphoma (CTCL) are a rare group of cancers that develop in the skin from T cells (a type of white blood cell). Mogamulizumab is a promising treatment for CTCL, but its most common adverse effect is a drug rash named mogamulizumab-associated rash (MAR). MAR remains poorly described, and it is difficult to tell apart from CTCL itself. In this study, we reviewed past records and followed up with all 24 patients with CTCL who were treated with mogamulizumab since it was approved for use in 2018 and seen by our institution in the USA. We saw a higher rate of MAR among our patients (71%) than previously reported, however, most of our patients had a specific type of CTCL (Sézary syndrome). Interestingly, most patients that developed MAR also responded well to mogamulizumab (88%), a higher rate than previously reported. Whereas patients that did not develop MAR did not respond to mogamulizumab as often. In our article, we describe the diverse patterns of MAR, which may or may not mimic CTCL both visually on the skin and under the microscope. A drug rash that can mimic the very disease the drug treats is dangerous to misdiagnose, especially if the rash is a sign that the drug is working; the drug might be discontinued before it has a chance to have a full effect on the cancer. Care providers should greet MAR as a sign that mogamulizumab works for that patient, and only consider discontinuing it if MAR is intolerable/resistant to treatment or the patient with CTCL goes into remission (i.e. the signs and symptoms of the cancer are reduced or gone) as a result of mogamulizumab. Linked Article: Trum et al. Br J Dermatol 2022; 186:153–166.