ABSTRACT: Most children with early or undifferentiated rash and fever have benign viral illnesses. However, the possibility of serious diseases must be ruled out. Thus, children who present with early or undifferentiated rash and fever may require further evaluation by appropriate specialists, and all require close follow-up. The distribution of the rash—whether central or peripheral—may be a clue to diagnosis. For example, lesions associated with varicella, Kawasaki disease, erythema multiforme, and staphylococcal scalded skin syndrome are initially located on or near the trunk. In some children, travel history may provide clues: some diseases are limited to certain regions of the country. Still other clues may be provided by the season (many illnesses peak at a specific time of year); the timing and pattern of the fever (eg, late afternoon or evening, early morning, recurring); or the presence of another key symptom, such as arthritis.
The sudden onset of rash and fever in a child frequently causes anxiety in parents. Fortunately, their worries are usually for naught. Most children who present with a rash and fever have a benign viral illness (whether or not it is easily identified). However, rash and fever can be the presenting signs of serious illness. Thus, it is vitally important in this setting that pediatricians be able to quickly review the differential diagnosis and determine whether a serious disease is likely.
In the previous 3 articles in this series (Part 1; Part 2; Part 3), I presented a triage system that can help clinicians quickly narrow the diagnostic possibilities and assess the likelihood of potentially serious illness. This system involves categorizing the patient's presenting symptoms into 1 of 3 groups:
• Group 1 includes children with symptoms of serious illness who require immediate intervention.
• Group 2 includes children with a clearly recognizable—and usually benign—viral syndrome.
• Group 3 includes children who present early in the course of the disease, when the clinical picture and physical findings are nonspecific, and those with undifferentiated rashes with fever. (Most febrile children with rash fall into this group.)
In the earlier articles in this series, I focused on children in the first two of these groups: those who present in obvious need of prompt intervention or with an easily recognizable viral exanthem. Here the focus is on children in group 3: those who present with early or undifferentiated rashes and fever. I discuss several types of clues—such as the distribution of the rash, the part of the country in which the patient fell sick, and the season of the year—that can help in your efforts to establish a diagnosis and rule out serious conditions.
EARLY OR UNDIFFERENTIATED RASHES WITH FEVER: GENERAL CONSIDERATIONS
The rashes associated with group 3 are the most perplexing of all. In children whose symptoms fall into group 1 or 2, the diagnosis is relatively straightforward. Those in group 3, however, lack some or most of the recognizable features of a specific disease. Differentiating between the potentially serious and the innocuous is extremely difficult. This is where you will earn your pay!
The vast majority of children with early or undifferentiated rashes and fever have benign viral illnesses that resolve spontaneously. Hidden among these, however, are the early and atypical presentations of the serious diseases discussed in earlier articles in this series. Thus, children in group 3 may require further evaluation and consultation with appropriate specialists.1 They also require close follow-up with good access to care. When there is concern about whether parents will be able to provide adequate care, it is sometimes necessary to admit the child.
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