Sir,We read with great interest the article by Salavastru et al.[1] on the incidence of viral exanthems and we agree with the authors on their recent outburst. We observed the same increase in the past 12 years.[23]What, in fact, did increase are the atypical exanthems,[3] while the classic forms have become less common. In Salavastru et al. article, for example, the varicella prevalence decreased in a single year by about 80%. Atypical exanthems are, therefore, becoming a serious diagnostic challenge and providing the physicians with an easy diagnostic tool is urgent. As they may be caused by infectious agents, drugs or by the interaction between viruses and drugs, especially important is the detection of the role of drugs. This, in fact, is crucial for the patient because the prompt discontinuation of the offending drug limits the severity of both rash and systemic involvement, and for pregnant women and immunocompromised patients. In our experience, the history of drug intake and general symptoms, the morphology of the exanthem and of the possible enanthem together with appropriate laboratory investigations may lead to an etiological diagnosis in over 70% of cases.In a study of ours[3] we found that 48% of cases were due to viruses, 19% to bacteria, 32% to drugs. Exanthems of unknown etiology were equally distributed among children and adults. The etiology was infectious in 70% of the children and 40% of the adults. Picornavirus (42%), adenovirus (15%), Epstein-Barr virus (EBV) (8%), rotavirus (6%), parvovirus B19 (5%), human herpes virus 6 and 7 (HHV-6 and HHV-7) (9%) and cytomegalovirus (CMV) (4%) were the prevalent viral agents. Viral infections prevailed in the spring and summer, especially when picornaviruses were implicated, and generally were associated with enanthems (83%), systemic symptoms (82%), involvement of the buttocks (96%), hands and feet (73%) or face (68%). The erythemato-vesicular pattern of the exanthem was significantly associated with enanthem and viral infections, especially picornavirus (74%), both in children and adults, whereas the maculo-papular pattern was indicative of iatrogenic etiology. Severe pruritus had an iatrogenic etiology in 95% of the cases, while the systemic symptoms had an infectious etiology in 82% of cases. A mixed etiology (carbamazepine and telaprevir plus HHV-6 and HHV-7) were found in three cases with severe systemic involvement (drug-induced hypersensitivity syndrome with eosinophilia). Routine laboratory investigations were not helpful, except the liver function tests for hepatitis viruses, EBV and CMV. Serology confirmed the viral isolation in 92% of the patients with viral infections and other methods as polymerase chain reaction may aid in the diagnosis.[3]Salavastru et al. emphasize the role of the immunization programs. In fact, the cases of classic exanthems we too observe are only sporadic, especially due to nonimmunized or partially vaccinated immigrants. The latter often present with atypical or attenuated forms which are difficult to diagnose, and only serology may be of aid as it was the case in seven patients with attenuated measles and five with atypical rubella of the series of ours.