Many parents have fever-phobia, their imagination running wild at the first hint of a raised temperature in their child. And the higher and faster the rise in the temperature, the faster and farther the imagination runs. During this time, the sudden appearance of a rash in their child sees parental anxiety turn to angst.
All children with a fever and rash need a thorough clinical examination to determine the likely cause and severity of the illness — both to commence prompt and appropriate treatment in the child as well as to assuage the now dread-filled parent. But don’t despair. That can all be done in 5-10 minutes for most presentations, as you swoop in with an all-encompassing approach and exclude conditions one-by-one — always willing to revisit and reconsider if the clinical picture remains unclear.
Before rushing in, keep in mind the less common non-infectious causes of fever with rash — such as drug reactions, cutaneous lupus, and cutaneous manifestations of inflammatory bowel disease. That said, in most circumstances, the child in front of you will have an infectious disease of one sort or another. The following features of the rash will help you to narrow-down your differential:
- Lesion characteristics
- Distribution and progression
- Timing of onset in relation to fever
- Morphological changes (e.g. papules to vesicles)
Characteristic features and the apparent urgency of the situation may necessitate treatment ‘on-spec’, before a complete history is taken — consider, for instance, the petechiae and purpurae that can accompany meningococcaemia. But in most cases there is time to take a more detailed history. And the time spent here will not go unrewarded. Details are important, but try to avoid getting bogged down in the minutiae of a symptom. Keep the parent focused on answering the question, but letting them “run” at times can be revealing.
[This is part of the art of history taking: knowing when to hold them, knowing when to fold them, and knowing when to run — so to speak. But don’t beat yourself up over it. Like any art, it takes time to maturity and requires practice and experience and only fully blossoms as you gain confidence and begin to relax. Avoid absorbing all that parental anxiety, but all the same do not be disinterested. Above all, show that you care: because you do care. An empathic but detached concern will allow you to maintain your professional boundaries while engaging with the child and parent. The ability to do this comes with experience. The level of detachment also may vary with your personal context: location; role; time; etc. Your job-description in the consultation is akin to that of a co-pilot — you’re not the only one flying the plane. Importantly, that means that there will be times when you need to take control of the plane.]
Your plan is to mentally marry the clinical features of the rash (above) to the patient context, obtained by noting the following:
- age of the patient
- travel history
- geographic location
- exposure to insects, animals, other people who are ill
- immune competency of patient (and immunisation history)
- other medical conditions
It is the time-course of the evolution of the presentation that is all-important (this will be a recurring theme in all your consulting). You do well to ascertain the following:
- was there a prodrome (early symptoms that might indicate the start of disease)?
- when did the rash start?
- where did the rash start?
- where has the rash spread to?
- has there been any change in the appearance or sensation of the rash etc.
- what has been used to treat the rash?
Finally, a review of systems is used to help rule out non-infectious causes (e.g. diarrhoea, weight loss, poor appetite, arthritis etc. for IBD and photo-sensitivity, malar or discoid rash, cytopenias, renal disease etc. for SLE).
Marrying rash features with clinical context of disease should now place you on a solid footing to make a presumptive diagnosis, from which you will communicate this effectively and institute therapy smartly.
Apart from meningococcaemia, always consider the following differentials in a child:
- Blanching erythematous maculopapular rash
- Begins in head and neck à spreads centrifugally to trunk and extremities
- Associated symptoms: fever, cough, coryza and conjunctivitis
- vesicular lesions on erythematous base appear in crops
- ‘dew drops on rose petals’ appearance
- lesions are present in different stages: papules, vesicles, crusting
- rash resembles measles, but patient is not ill looking
- prominent post-auricular, posterior cervical +/- suboccipital adenopathy
- Forschemier spots — petechiae on soft palate in 20% of patients
Erythema infectiosum (Fifth disease) – Human Parvovirus B19:
- characteristic rash that resembles “slapped cheeks”
- fleeting reticular (lacey) rash lasting a variable period after the acute illness subsides
Roseola infantum (Sixth Disease) or exanthema subitum – Human Herpes virus 6 and 7:
- sudden, high fever for 3-4 days followed by a raised, red rash which lasts for a few days
- very common, mild infection of children between the ages of six months and 3 years (rare after 4: 95% of children have been infected by age 2)
- may be followed by seizures
- spread by respiratory droplets before symptoms (fever and/or rash) appear
- generalized rash — trunk to extremities (face spared)
- exotoxin-mediated diffuse erythematous rash
- pharyngitis due to group A streptococcus
- coarse, sandpaper-like, erythematous, blanching rash → desquamation
- circumoral pallor and strawberry tongue
Non-polio enteroviruses (coxsackievirus, echovirus)
- cause variety of different rashes
- includes Hand-Foot and Mouth Disease, commonly due to Enterovirus 71
The non-infective inflammatory causes are:
- Acute Rheumatic Fever
- Kawasaki vasculitis
- Systemic Lupus Erythematosus (SOAP BRAIN MD mnemonic)
- Inflammatory Bowel Disease
Appendix A — Fever and Rash differential
- Approach to the Child with a Fever and Rash – Learn Pediatrics, The University of British Columbia. Available at http://learn.pediatrics.ubc.ca/body-systems/general-pediatrics/approach-to-a-the-child-with-a-fever-and-rash/ as at July 4, 2016