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Severe drug‐induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms in a 1‐month‐old infant with trisomy 21

Dear Editor, Druginduced hypersensitivity syndrome (DIHS) or drug reaction with eosinophilia and systemic symptoms (DRESS) is a lifethreatening allergic reaction to drugs, with a mortality rate of 10%.1 Cases of DIHS/ DRESS in early infancy or in infants with chromosomal disorders are rare; therefore, their prognoses remain unknown. Here, we report a severe case of DIHS/DRESS in a 1monthold infant with trisomy 21. Six days after starting phenobarbital for neonatal seizure, which developed on day 22, the patient developed fever, followed by erythema on his trunk, face, and extremities. He also had axillary and inguinal lymphadenopathy, and elevated liver enzyme and creatinine levels (aspartate aminotransferase, 433 IU/L; alanine aminotransferase, 629 IU/L; creatinine, 0.55 mg/dL; and Creactive protein, 12.89 mg/dL). He gradually developed erythroderma, metabolic and respiratory acidosis, and systemic shock, with the highest lactate level of 6.5 mmol/L. The patient was diagnosed with severe atypical DIHS/definite DRESS according to the specified criteria.2,3 The score of RegisCAR scoring system for DRESS2 and the composite scores for evaluating the severity of DIHS/DRESS4 were both 6. The diagnostic criteria for Kawasaki disease were not fulfilled. Viral infections were not ruled out; however, the reactivation of human herpesvirus (HHV)6 and cytomegalovirus (CMV) were not detected. HHV7 was not tested because of the limited sample volume. Skin biopsy was not performed considering the critical condition of the patient. To address his severe clinical findings, systemic steroid (prednisolone 2 mg/kg/day) and i.v. immunoglobulin (Ig; 500 mg/kg) were administrated, and phenobarbital was discontinued 5 days after the onset of erythema, which gradually regressed without any relapse. Prednisolone was tapered from 2 to 1 mg/kg/day over 3 days and then stopped (total, 8 mg/kg). The patient recovered from liver and renal dysfunctions and no longterm complications are apparent. This is the first severe case of DIHS/DRESS in an infant with trisomy 21 at 1month of age. Since systemic steroid and i.v. Ig are broadly administrated to treat DIHS/DRESS, their types or doses are not widely recognized and they have a risk of triggering short and longterm autoimmune diseases.5 Despite the severity, we successfully treated the patient using prednisolone and Ig without relapse or complications. It has been reported that some viral reactivation, such as CMV, is associated with duration or relapse of symptoms and complications.4 The reactivation is more likely to occur with rapid reduction of systemic steroid or i.v. Ig.5 We assume this case was successfully treated with a short course in the absence of viral reactivation. Previously, fatal outcomes in a 3monthold infant and a patient with chromosomal translocation have been reported.1 We presume that DIHS/DRESS in patients in early infancy or with chromosomal disorders may potentially become severe because of the patients’ frailty. The present case also cautions against an increased risk of DIHS/ DRESS among patients with neonatal seizures. Physicians should be aware of this syndrome and consider the risk of aggravation, especially in the case of infants and those with chromosomal disorders (Figure 1). The treatment course must be prompt and proper to prevent exacerbation and adverse effects of aggressive therapy.