Association of Immunologically Confirmed Delayed Drug Reaction and Human Herpesvirus 6 Viremia in a Pediatric Case of Drug-Induced Hypersensitivity Syndrome

child was seen for febrile lower back pain. An epiduritis was suspected on clinical signs, biology and spine MRI. No bacteria were isolated from blood culture and lumbar puncture. Antibiotics were initiated with cefotaxime and rifampicin for 2 weeks. Then the child received oral rifampin and trimethoprim/sulfamethoxazole. The child had never received these antibiotics before. Four weeks later, he presented a progressive generalized rash associated with hyperthermia and severe asthenia and was referred to our unit. Exanthematous eruption, diffuse edema ( fig. 1 ) and severe pruritus were observed on examination; in addition, polyadenitis and splenohepatomegaly were noted. The laboratory results revealed leukocytosis (WBC: 68,000/mm 3 , absolute eosinophil count: 1,800/mm 3 ) with mononucleosis, cholestasis and hepatic cytolysis (alkaline phosphatase: 623 IU/l, aspartate transaminase: 430 IU/l, alanine transaminase: 265 IU/l). Polymerase chain reaction for HHV-6 performed on day 3 after the onset of the rash was positive in blood (65,000 copies/ml). Cytomegalovirus and Epstein-Barr virus serologies were negative. The diagnosis of DIHS was made, and all drugs were discontinued. Corticosteroid therapy was started (prednisone 1 mg/kg/day) resulting in a rapid resolution of DIHS symptoms without epiduritis recurrence. Corticoids were stopped within 2 weeks without relapse. Two months later, drug patch tests were performed with the commercialized forms and with the purified active agent of all suspected antibiotics (drugs series, Chemotechnique , Sweden) in accordance with the guidelines for drug patch testing [1] . The patch tests were ap