The role of frozen section in the rapid diagnosis of severe cutaneous adverse drug reactions

Context: Early diagnosis is the mainstay in the management of severe cutaneous adverse reactions (SCARs) to drugs. Aims: To study the role of frozen section in the rapid diagnosis of SCARs and the impact on outcome of the affected patients. Settings and Design: A single-blind, hospital-based study was conducted from December 2014-July 2016. Methods and Material: We biopsied 32 adults with SCARs diagnosed by clinical features and standard criteria. The histopathological features seen on frozen sections were compared to that of paraffin blocks. The impact of rapid diagnosis on the clinical outcome was studied in toxic epidermal necrolysis (TEN), Stevens-Johnson syndrome (SJS), drug rash with eosinophilia and systemic symptoms (DRESS) and acute generalized exanthematous pustulosis (AGEP). Statistical Analysis: Z test was used to compare two proportions. Kappa statistic, sensitivity, specificity, positive predictive value, and negative predictive value of the frozen section diagnosis were calculated in TEN/SJS and DRESS using MedCalc software. Results: Frozen and paraffin sections were done in TEN/SJS spectrum (13), DRESS (17), and AGEP (2). The sensitivity, specificity and kappa values for frozen section diagnosis in SJS/TEN and DRESS were 91.7%, 95%, 0.867 and 94.4%, 100%, 0.937 respectively. The concordance between frozen and paraffin section diagnosis was 100% in TEN, SJS, DRESS and AGEP. All the 6 patients with TEN and 2 with AGEP survived. Taking the worst-case scenario, the mortality in SJS was 28.6%. The mortality among patients with DRESS was 11.8%. Conclusions: Frozen section helps in the rapid diagnosis and early treatment of SCARs and differentiates it from diseases that mimic it.