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 their imagination runs.
During this time, the sudden appearance of a rash in their child sees parental anxiety turn to outright angst.
All children with a fever and rash need a thorough clinical examination to determine likely cause and severity of illness, both to commence prompt and appropriate treatment in the child as well as to assuage the now dread-filled parent. That takes about 5-10 minutes for most presentations with an all-encompassing approach excluding conditions one-by-one; always willing to revisit and reconsider if the clinical picture warrants.
Before rushing in, however, keep in mind less common non-infectious causes of fever with rash such as drug reactions, cutaneous lupus, and cutaneous manifestations of inflammatory bowel disease. But, 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 which one:
- Lesion characteristics
- Distribution and progression
- Timing of onset in relation to fever
- Morphological changes (e.g. papules to vesicles)
Characteristic features and 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. Finally, children are brilliant historians as they bring an unadulterated perspective to their condition, and usually free of ulterior motive.
[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. Like any art, it takes time to maturity and requires practice and experience, only fully blossoming as you gain confidence and begin to relax. Avoid absorbing too much parental anxiety, but all the same do not be disinterested. Show that you care. Be genuine. 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 may vary also with your personal context: location; role; time; etc.]
Your plan is to mentally match clinical features of the rash to the patient context obtained by noting the following:
- patient age
- season
- travel history
- location – geography
- exposures — insects, animals, other people who are ill
- medications
- immunocompetency — and immunisation history
- other medical conditions
The time-course of the evolution of the presentation is all-important. (This will be a recurring theme in all your consulting).
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 helps rule out the 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 puts you on firm footing to make a provisional diagnosis, from which to communicate effectively to carers and institute therapy smartly.
Apart from meningococcaemia, always consider the following differentials in a child:
Measles:
- Blanching erythematous maculopapular rash that begins in the head and neck and spreads centrifugally, to trunk and extremities
- Associated symptoms: fever, cough, coryza and conjunctivitis
- Children with measles are usually quite sick.
- Look for buccal lesions: clustered, white lesions on the buccal mucosa, opposite the lower 1st and 2nd molars. These Koplik spots are said to be pathognomonic for measles.
Chickenpox:
- vesicular lesions on erythematous base appear in crops (groups) and at different stages of evolution: papule → vesicle → crusting
- “dew-drops on rose petals” appearance
Rubella:
- rash resembles measles, but
- patient not ill looking
- prominent post-auricular, posterior cervical +/- suboccipital adenopathy
- Look for petechiae on soft palate (Forschemier spots), found in 20% of patients but unlikely to be very specific
Erythema infectiosum (Fifth disease) – Human Parvovirus B19:
- characteristic rash 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)
Scarlet fever:
- exotoxin-mediated diffuse erythematous rash
- pharyngitis due to group A streptococcus – in my experience, this often has an iridescent strawberry colour to the pharyngitis
- 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
Some illnesses are associated with a typical rash, which can suggest a definitive diagnosis. In other cases, the clinical features may not be specific enough to enable an accurate diagnosis. Six separate childhood exanthems were defined at the turn of the twentieth Century. These were named in the order they were discovered.²
Dukes Disease is now thought to be a variant of scarlet fever—others suggest that it is Staphylococcal scalded skin syndrome—and its term, “Fourth Disease”, is no longer used. Chickenpox (infectivity subsided once all the lesions have crusted over) and Small Pox were two other classic childhood exanthems recognised as separate from one another in the 18th century. Measles, Scarlet fever, and Rubella are notifiable diseases.²
Children commonly present to the emergency department (ED) with a febrile illness and a rash. Approximately 70% of such cases are attributable to viruses, such as coxsackie, echovirus or the enteroviruses. The rest result from bacterial infections such as streptococcal and staphylococcal infections, mycoplasma, rickettsial diseases, drug-related causes or Kawasaki disease.²
Appendix A — Fever and Rash: Differential
References
- Chamberlain, Neal. Skin Rashes: Diseases 1-6”. A. T. Still University of Health Sciences. November 12, 2013. Available at https://www.atsu.edu/faculty/chamberlain/exanthems.htm. Accessed September 6, 2020.
- Naravi, May; Berry, Kathleen; and Perry, Michael. “Common Childhood Exanthems.” Royal College of Emergency Medicine (RCEM) Learning. January 15, 2018. Available at https://www.rcemlearning.co.uk/reference/common-childhood-exanthems/#1568715339434-be9f1431-eaae. Accessed September 6, 2020.
- Steichen, O; Dautheville, S. (2009). “Koplik spots in early measles.” CMAJ. 2009 Mar 3; 180(5): 583.
- Yao, Ying and Statham, Elmine. “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/. Accessed July 4, 2016.
Downloads
- Fever and Rash: Childhood Exanthems TGDvar pdf – updated Mar 2021
- Evaluating the Febrile Patient with a Rash, AAFP
