In‐vivo and ex‐vivo tests for culprit drugs identification in severe cutaneous adverse drugs reactions

Drug causality assessment in severe cutaneous adverse reactions (SCARs) remains challenging. We investigated the usefulness of in‐vivo drug patch tests (PT), ex‐vivo interferon (IFN)‐γ enzyme‐linked immunospot (ELISpot) assay, and lymphocyte transformation test (LTT) in 30 SCARs patients within the past 36 months. Drug PT yielded a 20% positivity rate ( n = 6), while IFN‐γ ELISpot and LTT showed positive rates of 56.67% ( n = 17) and 41.38% ( n = 12), respectively. Combining the three tests resulted in an overall positive rate of 66.67% ( n = 20) of cases. IFN‐γ ELISpot offered additional positivity, especially with oxypurinol. Employing a combined diagnostic approach may enhance the chances of obtaining a positive result.