Paediatric Erythematous Rash

Differential

• Coxsackie virus
• Echovirus
• EBV 
• Adenovirus
• Parainfluenza
• Influenza
• Parvovirus B19
• HHV-6
• Rubella
• Measles
• Drug reaction
• Mycoplasma
• Systemic juvenile idiopathic arthritis

Always consider

• Septicaemia
• Scarlet fever
• Kawasaki disease
• Toxic shock syndrome
• Toxic epidermal necrolysis
• Stevens-Johnson syndrome

Fever and exanthem

• Most commonly viral
• Is the child sick, lethargic or very young?
  • Consider meningococcal (can be erythematous early), bacterial sepsis, Kawasaki, TSS, TENS, SJS
• Is the child on medications?
  • Consider drug reaction
• Are other people at risk?
  • If relatives are immunosuppressed or pregnant, consider serology, stool viral culture and education of relatives
• Is the rash papular?
  • Consider papular acrodermatitis (see next)
• Is the rash itchy?
  • Primary urticaria or dermatitis

Papular acrodermatitis
(i.e. Gianotti-Crosti)

• Occurs in children 1-3yo (mostly)
• Reaction to Coxsackie, echovirus, Mycoplasma, EBV, adenovirus, RSV, rotavirus, CMV, HepB and any vaccination
• Acute onset of monomorphic, red or skin-coloured papules mainly on limbs, buttocks and face with STRIKING SPARING OF TRUNK
• May coalesce into patches on extensor surfaces
• May be papulovesicular on limbs or purpuric on the face
• May be itchy
• Complete resolution takes 4-8 weeks
• No exclusion period required and just needs reassuranc

Scarlet fever

• Group A streptococci
• Usually school-age children
• Need to consider post-strep GN, acute RF, TSS, necrotising fasciitis
• Prodrome of sudden onset of high fever, vomiting, malaise, headache and abdominal pain
  • Within hours, typical rash appears: Diffuse, pink-red flush with pinhead spots (feels like sandpaper)
  • Flushed face with circumoral sparing
  • Does not usually involve palms or soles
  • Strawberry tongue (white then red day 4-5)
  • Pharyngotonsillitis, tender nodes
• Confirm by throat swab and serology
• Isolate for 3 days after start of treatment
• Treat with oral Pen V

Toxic shock syndrome

• Seen with S. aureus and Group A strep
• Similar to scarlet fever but includes myalgia, profuse diarrhoea, conjunctival injection and hypotension
• Desquamation occurs of peripheries at 7-21 days
• Treatment
  • Flucloxacillin + Clindamycin (to inhibit toxin release)

Kawasaki disease

• Children 6 months to 5 years (mostly). 1.5x more common in boys. Peak age 18-24 months
• Consider in all children with fever, red eyes and rash as well as all prolonged fever cases
• High fever persisting for 1-4 weeks with severe irritability unresponsive to antipyretics
• Dilatation of conjunctival vessels seen within few days of fever onset but may be transient (therefore need to ask!) with no conjunctivitis or purulent discharge
  • Sparing of perilimbic area (as avascular)
• 60% of children have enlarged cervical nodes
• Older children may have striking unilateral tender cervical lymphadenopathy (confused with lymphadenitis but does not respond to antibiotics)

• Within days of fever onset, 90% of children develop widespread erythematous rash
  • Usually anogenital area involved
  • No vesicles or crusting. May be morbilliform, maculopapular or scarlatiniform
  • Rash lasts 1-7 days
• Within day or two of rash, 90% develop red, dry, fissured lips and mouth (can persist 2–3 weeks)
• Within day or two of rash, erythema of palms/soles occurs in 95% of children often with associated oedema
• Desquamation begins 2 weeks after onset of fever, begins at finger tips and spread to involve palms, toes then soles

• Pathophysiology
  • Suspected viral aetiology but not identified
  • Vasculitis of medium-sized vessels including coronary, renal, splanchnic
• Diagnostic criteria
  • Fever at least 5 days + 4/5 of:
    • Bilateral conjunctival injection
    • Exanthem: Dry, cracked lips, oropharyngeal erythema, strawberry tongue
    • Exanthem: Polymorphous
    • Peripheral changes: Erythema (palms/soles) and/or oedema of hands and feet
    • Cervical adenopathy (at least one node >1.5cm)

• Less common findings
  • Anaemia, Arthritis, diarrhoea, vomiting, coryza, cough and hydrops of gallbladder
  • Aseptic meningitis
  • Sterile pyuria
• Atypical cases
  • Children <6 months and sometimes older children may present with prolonged fever and only 1-2 of above features
  • Cervical lymphadenopathy is absent in 90% of cases
  • Rash absent in 50% of cases
  • Mucous membrane changes present in 90% of both typical and atypical cases
  • Coronary artery aneurysms are more common in these cases (RCH)

• Untreated, 25% of cases suffer coronary artery aneurysm
  • Can take 6-8 weeks to arise and may be fatal
• Concurrent infections present in 40% so positive NPA does NOT rule out KD
• Any child with fever 5 days and 2 clinical criteria OR infants with fever for 7 days
  • FBC, ESR, LFT, Group A strep serology
    • Usually marked leukocytosis, ESR and CRP elevated
    • Marked thrombocytosis seen in week 2-3
  • If Kawasaki suspected, echo should be performed at presentation and again at 6-8 weeks

• Treatment
  • IVIG prevents development of coronary aneurysms in dose-dependent fashion
  • Aspirin (25mg/kg QID) as early as possible in course of illness and until afebrile
  • Steroids considered in high risk cases in concert with Paediatrics as suggested by signs of shock, age <12 months, Asian, ALT >100, Albumin <30 or cardiac changes
  • If ongoing fever beyond 36 hours of IVIG should receive second dose
  • IVIG + Steroids better than IVIG alone
• Prognosis
  • Mortality <1%
    • Highest in <12 mo
  • Recurrence rate of 4%, mostly in those under 3yo and with cardiac involvement. Usually within 12 months
  • Most small-to-medium aneurysms resolve on echo but healing involves scarring of unclear significance

• Complications
  • Coronary artery dilatation (ectasia) and aneurysms
  • Can have perivascular brightness, ectasia and lack of tapering to suggest arteritis
  • May see decreased LV contractility, MR and pericardial effusion also

Erythema infectiosum

• Slapped cheek disease/Fifth disease
• Parvovirus B19
• Non-specific prodrome of fever, myalgia, headache and malaise in 15-30%
• Distinctive rash in 3 stages:
  • Slapped cheek (1-3 days)
  • Maculopapular blanching rash on trunk and flexor/extensor surfaces
    • Central clearing and reticular pattern over 7 days
  • Reticular rash reappears with cold/heat/friction (weeks/months)
• Treatment is supportive
• Highly infective prior to rash only so no exclusion
• Pregnant women have risk of foetal anaemia and death but exclusion is not practical

Roseola infantum

• Common viral exanthem due to HHV-6 (+- HHV-7)
• Almost all infants exposed to this, but only 30% show clinical features
• High fever for 2-4 days but looks well
• Occipital and cervical lymphadenopathy arise
• Fever disappears and widespread erythematous rash appears on face and trunk
• Child remains well and often presents to ED like this
• Supportive therapy only

Hand, foot and mouth

• Coxsackie A16 virus usually
• Self-limiting
• Need to ensure hydration

Infectious mononucleosis

• Mostly EBV but can also be CMV
• DDx of heterophile antibody negative IM (often with neutrophilia vs. lymphocytosis)
  • CMV
  • Toxoplasmosis
  • HIV
• Fever, generalised lymphadenopathy, exudative tonsillopharyngitis, palatal petechiae and hepatosplenomegaly
• Rash may be erythematous, maculopapular or morbilliform
• Children usually mild illness compared to adults
• Rash seen in 20% in first few days
  • Increased if given amoxicillin or other penicillins

• Diagnosis confirmed by FBC, LFT and serology
• Isolation not required
• Oral prednisolone for 5 days can assist resolution
• Children with splenomegaly should avoid contact sports until resolved
  Monospot

Measles

• Cough, conjunctivitis and rash
• Rash appears 3-4 days after prodrome of fever, conjunctivitis, cough, coryza and Koplik spots on buccal mucosa
• Rash is red, blanching, morbilliform starting from ears/hairline and spreads to limbs
  • Confluent by third day
  • High fever often persists
• Complications include pneumonia, otitis media and encephalitis
• Subacute sclerosing panencephalitis is a rare, fatal, late complication
• Exclude for 5 days
• If unimmunised child contacts measles over 9 months of age, measles can be prevented by MMR within 72 hours
• Unimmunised exposed contacts at high risk of complications (Infants <12mo, pregnant women and immunocompromised) should receive normal human immunoglobulin within 7 days

Atypical measles

• Measles exposure in vaccinated children
• High fever, malaise, no cough/conjunctivitis/Koplik spots and rash is more distal and often purpuric

Rubella

• German measles
• Asymptomatic in 25-50% of children
• If affected, often only mildly unwell
• Prodrome for 5 days of low-grade fever, malaise, headache, coryza, post-auricular/occipital/posterior chain lymphadenopathy
• Rash is small, fine, discrete, pink maculopapules starting on face/trunk and spreading to whole body within 24 hours (centripetal)
• If unvaccinated or <1yo (not received full schedule at that age) can consider this and confirm with IF and culture of nasal or throat swab
• Exclude for 5 days
• Pregnant women should receive counselling if in contact

Unilateral laterothoracic exanthem

• 1-4yo mild fever with GI or URTI symptoms 1-3 weeks before onset of rash
• Begins in one axilla or side of chest as erythematous, urticarial, eczematous or papular lesions
• Over a week, rash spreads to give striking unilateral involvement of chest/axilla and arm
• Over next 2 weeks may spread further
• Complete resolution takes 4-6 weeks
• No causative agency known
• Treatment not usually required but can consider topical corticosteroids

Urticaria

• Rapid appearance and disappearance of multiple raised wheals
• Often itchy
• May have central sparing but are not target lesions (as these last days)
• Often leave some purplish non-blanching area suggesting capillary leak of blood
• Features that suggest underlying vasculitis:
  • Wheals lasting >24 hours, bruising within wheals, painful lesions, associated fever/arthralgia/abdominal pain or haematuria

• Most common causes
  • Viral or bacterial infection
  • Environmental/food allergen are infrequent causes
    • Nuts, eggs, shellfish, strawberries, tomatoes, cow’s milk
  • Drugs
    • Penicillin/cephalosporins, aspirin, NSAID’s, latex
  • Can be precipitated by sunlight, pressure, water, cold, heat
• Rarely last longer than 3 months and usually resolve over days/weeks
• If unwell with urticaria, consider anaphylaxis or Kawasaki disease
• If individual lesions last >2 days, consider HSP or vasculitis

• DDx
  • Erythema multiforme
    • Usually not itchy
    • Does not move around (i.e. fixed)
    • Target lesions typical
    • Often mucosal involvement
  • Mastocytosis
  • Flushing
  • Juvenile RA
  • HSP
  • Pityriasis rosea

• Management
  • Always consider anaphylaxis (or C1 esterase inhibitor deficiency if no angioedema with no wheals)
  • Treat itch with oral antihistamine
  • Oral prednisolone may be utilised if severe itch
  • If any purpura or unwell, consider meningococcal
  • If sun-induced, painful urticaria, consider erythrocyte protoporphyria

• For recurrent/chronic cases consider:
  • Trigger factor history
  • Throat swab for GAS carriage
  • FBC (eosinophilia or anaemia)
  • IgE
  • ANA
  • Urine culture for bacteraemia
  • Nocturnal check for threadworms

Serum sickness

• Triad of fever, urticaria and arthralgia
• 50% idiopathic and 50% associated with recent cefaclor course
• Can be seen after antivenom use
• Usually 5-21 days after commencement of cefaclor
• Symptoms resolve within days
• Oral antihistamines may provide symptom relief and a few days of oral steroids if severe symptoms

Systemic lupus erythematosus

• May present as erythematous, well-demarcated facial lesions in children
• Usually butterfly distribution (malar rash)
• May be the only manifestation in children (cutaneous lupus)
• If more widespread:
  • Scaly lesions on ears/neck/limbs
  • Erythematous macules/petechiae around nail beds and tips of fingers/toes
  • Erythematous macules on palms/soles
• Systemic involvement
  • Fevers, arthralgias and arthritis
  • Lymphadenopathy, anorexia, weight loss, muscle weakness, pleuritis, myocarditis, nephritis and neuropsychiatric presentations may also occur

• Workup
  • ANA, anti-dsDNA, ESR, FBC, renal assessment +- brain imaging
• Treatment
  • Localised cutaneous lesions respond to moisturiser, sun protection and potent steroids
  • Systemic disease usually requires oral steroid therapy

Neonatal lupus erythematosus

• Occurs in 5% of infants born to anti-Ro and/or anti-La positive mothers
• Around 50% get cutaneous lesions and 50% complete heart block (rarely both)
• Can present from days to months after birth
• Widespread, erythematous, annular lesions persisting months before maternal antibodies clear
• Moderate potency topical steroids assist clearance
• Complete heart block
  • Arises in third trimester and is permanent and fatal if no pacemaker

Dermatomyositis

• Children may present with skin changes years before muscle symptoms
• Usually erythematous, violaceous rash on eyelids, periorbital oedema, malar erythematous rash and erythematous papules on extensor surfaces of hand joints
• Muscle weakness may or may not be evident
• Ix: ESR, FBC, CK, MRI of muscle
• High-dose oral corticosteroids are required

Erythema nodosum

• Fairly abrupt onset of painful and tender subcutaneous erythematous lesions, mainly on anterior lower legs
• Malaise, fever and arthralgia may also be evident
• 50% of cases have associated systemic illness
  • Chronic streptococcal disease
  • Tuberculosis
  • IBD
  • Chronic GI infections
  • Sarcoidosis
  • Mycoplasma
  • Lymphoma
  • Secondary syphilis
  • Deep fungal infection
  • OCP use

• Resolution over 3-6 weeks usually (like a bruise)
• Management
  • Search for underlying cause
    • Consider throat swab, FBC, ESR, GAS serology, Mycoplasma serology, EBV serology, stool culture, Mantoux testing and X-ray
  • Bed rest and limitation of activity for a few days if symptoms severe
  • NSAID’s help with pain/inflammation
  • Potassium iodide PO if prolonged or recurrent

Palmoplantar hidradenitis

• Seen in healthy 2-14 yo children in spring/autumn
• Often hx of exertion in days prior, often with exposure to cold/water
• Erythematous, dusky tender lesions on soles and sometimes hands
• Often due to Pseudomonas infection in sweat glands
• Resolves spontaneously

Erysipelas

• More acute and severe onset of symptoms vs. cellulitis
• Fevers, chills, malaise, headache
• Clear demarcation of involved and uninvolved tissue
• Raised advancing border with central clearing
• Butterfly distribution
• Milian’s ear sign
  • INvolvement of the ear is only from erysipelas (as lacks deeper dermal tissue to cause cellulitis)
• Mostly beta-haemolytic strep

Cellulitis

• Deeper dermal infection
• Beta-haemolytic strep (A, B, C, G and F)
• Staph is less common but does occur
• Animal bites
  • Pasteurella multocida and Capnocytophaga canimorsus
• Saltwater
  • Vibrio
• Freshwater
  • Aeromonas
• Immunocompromised/DM
  • Pseudomonas

Last Updated on November 22, 2021 by Andrew Crofton