To determine serum and/or blister‐fluid total HMGB1 levels in SJS/TEN cohorts, and HMGB1 expression in formalin‐fixed, paraffin‐embedded (FFPE) SJS/TEN skin vs. healthy and maculopapular exanthema (MPE) skin. This evidence concerns the gene HMGB1 and toxic epidermal necrolysis.