Acute generalized exanthematous pustulosis associated with polysensitivity to paracetamol and bromhexine: the diagnostic role of in vitro interferon-gamma release test.

We report a patient with acute generalized exanthematous pustulosis (AGEP), which occurred 3 days after ingesting paracetamol and bromhexine. Both were immediately stopped and the rash resolved rapidly. To determine the offending drug responsible for AGEP, an in vitro drug-induced interferon (IFN)-gamma release test was performed using an ELISA technique. Increased IFN-gamma release was observed following in vitro challenge of the patient's lymphocytes with paracetamol or bromhexine (110% and 157% increase, respectively). In vitro challenge with paracetamol or bromhexine in a control patient, treated with paracetamol and bromhexine, did not induce an increase in IFN-gamma. These findings suggest that the patient with AGEP may have polysensitivity to both drugs. The ELISA assessment also demonstrates the relevance of in vitro cytokine release tests in the investigation of such dermatoses.