An infant case of severe hypereosinophilia and systemic symptoms with multiple drug hypersensitivity and reactivation of cytomegalovirus and BK virus.

Hypereosinophilia (i.e. a blood eosinophil count exceeding 1.5 109/L) can be caused by various triggers including numerous allergic, infectious, and neoplastic disorders, and intrinsically cause tissue and organ damage, regardless of underlying cause. Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome/drug-induced hypersensitivity syndrome (DIHS) is a rare, potentially life-threatening adverse drug-induced reaction with cutaneous manifestations and internal organ involvement.1,2 Reactivation of herpesviruses, including human herpesvirus-6 (HHV-6), HHV-7, cytomegalovirus (CMV), and EpsteineBarr virus (EBV), has been shown to play a role in DRESS/DIHS pathogenesis.2,3 Here, we report an infant case with severe hypereosinophilia accompanied by cutaneous, cardiac, and pulmonary manifestations, and reactivation of CMV and BK virus (BKV). A previously healthy 17-month-old girl was referred to our institute on the 2nd day of illness because of high-grade fever and skin eruption. The patient had a cough and low-grade fever, and thus received pranlukast and azithromycin (AZM) from ten days and four days before the visit, respectively. The patient had no history of allergies, but had a family history of drug allergy. On admission, her temperature was 38.8 C; blood pressure, 108/62; heart rate, 180; respiratory rate, 38; and oxygen saturation, 94% in room air. Reticulated erythema spread from trunk to extremities, but not intomucosa and conjunctivas. Physical examination revealed cervical lymphadenopathy without hepatosplenomegaly. Laboratory findings revealed leukocytosis and eosinophilia with white blood cell count of 39.8 109/L with 54% eosinophils (21.5 109/L), 20% neutrophils, 21% lymphocytes, and 1.0% atypical lymphocytes. The blood chemistry results including hepatic enzymes were not notable. Immunoglobulin G, A, M and E were within the agematched normal range. Pathogens were not isolated from blood, urine, or stool culture. Rapid antigen tests for respiratory syncytial virus, mycoplasma, and adenovirus were negative. Serologic tests revealed absence of active infection of CMV, EBV, humanparvovirus Bl9 (hPV-B19), human immunodeficiency virus, hepatitis viruses, and HHV-6. Pneumonia was observed on the chest radiograph, and deteriorated with progression of desaturation, in spite of treatment with ampicillin/sulbactam. A chest computed tomography scan on the 4th hospital day revealed a mixture of ground-glass opacities and