Viral rashes mimicking drug reaction with eosinophilia and systemic symptoms syndrome in children after β-lactams intake: a diagnostic challenge.

In cases of skin eruptions over the course of antibiotic therapy and concomitant viral infection, differential diagnosis is often challenging. Confirming or ruling out drug hypersensitivity is not always a clear-cut question. Drug reaction with eosinophilia and systemic symptoms (DRESS) cases, for example, is classified as severe cutaneous adverse reactions due to drugs, but frequently the clinical manifestations do not completely fit into the diagnosis of DRESS. The aim of the present paper is to highlight similarities and differences among DRESS syndrome and DRESS-like rashes during viral infections and amoxicillin intake in children, in order to highlight those aspects that can help clinicians in early detection. We describe the dermatological, clinical, and laboratory characteristics of five patients hospitalized for DRESS-like skin rashes appearing roughly 1 week since the start of an amoxicillina course for upper respiratory tract infection (URTI) symptoms. The data are compared with those of 3 patients with early-onset DRESS syndrome. The absence of eosinophilia might be an initial marker to help identifying DRESS-like rashes; a quick clinical improvement and the confirmation of a viral infection able to explain the symptoms can help to finally rule out DRESS syndrome. Conclusion: A rapid, correct diagnosis of such DRESS-like rashes during viral infections allows more appropriate management and avoids unnecessary, life-long exclusion of useful and effective antibiotics because of a falsely "amoxicillin-allergy" labelling. What is Known: • Viral infections are common causes of skin rashes in children during antibiotic intake and may require differential diagnosis with drug reactions. • Early-onset DRESS syndrome is usually induced by antibiotics and appears ≤15 days after drug intake. What is New: • Prominent midface edema, maculopapular rash, and mild-to-moderate systemic symptoms may appear in children during viral illnesses treated with amoxicillin few days after drug intake, and may require differential diagnosis with early-onset DRESS. • In such cases, absence of eosinophilia, low (2-3) RegiSCAR score, confirmation of viral etiology, and a rapid resolution of the rash (2-5 days) might help to rule out DRESS; conversely, at an early stage, the presence of eosinophilia should suggest a diagnosis of DRESS.