Tetrazepam is a benzodiazepine that is widely used in Spain as a muscle relaxant, with occasional cutaneous side effects. We report a patient who developed a generalized pruriginous cutaneous reaction compatible with acute generalized exanthematous pustulosis (AGEP) due to tetrazepam. Patch tests with bromazepam, diazepam, and tetrazepam were negative at 48 and 72 hours; however, the tetrazepam patch showed a positive reaction at 10 days. Immunohistochemical studies revealed a mononuclear infi ltrate composed of CD4+ and CD8+ T lymphocytes. Analysis of interleukin (IL) 8 expression by quantitative polymerase chain reaction revealed increased IL-8 mRNA levels in patch test-positive skin. Lymphoblast transformation test (LTT) was positive with tetrazepam but not with diazepam. Positive patch test and LTT suggested that tetrazepam-specifi c lymphocytes might be responsible for a T cell-mediated reaction. These results support previous data suggesting an important role for IL-8 and drug-specific T cells in the pathogenesis of AGEP and imply that the reaction was specifi c
to tetrazepam with no cross-reactivity to other benzodiazepines.

Key words: Acute generalized exanthematous pustulosis. Benzodiazepines. Drug reaction. Interleukin-8. Lymphocyte transformation test. Patch test. Tetrazepam.