A case of drug-induced hypersensitivity syndrome (DIHS)/drug reaction with eosinophilia and systemic symptoms (DRESS) following stomatitis

Drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (DIHS/DRESS) is a severe form of drug-related rash with distinct features. This condition is characterized by late onset from specific causative drugs, and symptoms worsen despite discontinuation of the causative agent, followed by organ dysfunction. Notably, DIHS/DRESS results from the reactivation of human herpesvirus 6 (HHV-6). Herein, we report a case of DIHS/DRESS in which rash, fever and liver dysfunction were observed during hospitalization for stomatitis, and HHV-6 reactivation was confirmed. A 67-year-old man who had been taking carbamazepine for the sequelae of cerebral hemorrhage was referred to our hospital because of pain in the oral mucosa. Initially, he was diagnosed with a herpes virus infection and treated with acyclovir. Afterward, despite improvement in stomatitis, papules appeared on the trunk of the body and worsened. The symptoms were accompanied by fever and liver dysfunction. Eventually, the patient developed decreased systolic blood pressure, tachypnea, and atrial fibrillation. After pulse steroid therapy was initiated, the patient's clinical condition improved. Real-time polymerase chain reaction was performed suspecting with DIHS/DRESS, and HHV-6 DNA was detected. Based on this process, we diagnosed the patient with DIHS/DRESS induced by carbamazepine.