Needing a Diagnostic Kick-start

aka Paediatric Perplexity 008

A 4 year-old boy has been brought to the emergency department by his worried parents. He has had fevers for the past 6 days. They are concerned because he is not getting better despite repeated visits to a number of doctors. Each time they were told he had a viral illness.

On examination you note the presence of bilateral conjunctivitis, and erythematous rash on his torso and limbs, a 4 cm tender left-sided cervical lymph node and a diffusely red pharynx.


Q1. What is the likely diagnosis?

Answer and Interpretation

Kawasaki disease

Also known as Mucocutaneous Lymph Node Syndrome (MNLS), this vasculitic disorder was first described by Dr. Tomisaku Kawaski in 1967. It is of uncertain etiology, but may be a post-infectious condition.


Q2. How is this diagnosis made?

Answer and Interpretation

The diagnosis is made on the basis of the following clinical criteria (A + B):

A.Fever ≥5 days

B. At least 4 of the 5 following physical examination findings:

1. Bilateral, nonexudative bulbar conjunctival injection. Bilateral scleral injection with perilimbic sparing
2. Oropharyngeal mucous membrane changes. Pharyngeal erythema, red/cracked lips, and a strawberry tongue
3. Cervical lymphadenopathy. With at least one node >1.5 cm in diameter.
4. Peripheral extremity changes 
The diffuse palmar erythema seen in KD is in contrast to the discrete macular lesions of various viral illnesses (e.g., measles) that can sometimes be seen on the palms and soles.
– acute phase
: diffuse erythema and swelling of the hands and feet.
– convalescent phase: periungual desquamation (weeks 2 to 3)
5. A polymorphous generalized rash. Nonvesicular and nonbullous. There is no specific rash that is pathognomonic for KD

The manifestations may appear sequentially rather than concurrently. Atypical cases may not meet all the criteria but may still have the same risks of cardiac complications. These ‘incomplete’ cases occur more often in infants less than 6 months-old — further investigations (see Q5) should be performed if fever of 5 days and 2 or 3 of the other criteria are present.

Clinicians should have a high index of suspicion for this diagnosis in any child with a prolonged fever as early diagnosis and treatment may help prevent the potentially fatal complications of Kawasaki disease.

The approach to ‘incomplete’ Kawasaki disease is summarised nicely in this Paucis Verbis card from Academic Life in Emergency Medicine: Kawasaki disease.

Physical findings consistent with Kawasaki disease


Q3. Who gets this condition?

Answer and Interpretation

Kawasaki disease may occur in any child of any age, and even adults in some cases.

However, it is more common in:

  • children aged < 5 years
  • Asians
  • males (RR 1.5)

Q4. What are the important differential diagnoses?

Answer and Interpretation

Diagnosis may be difficult as Kawasaki disease may mimic a number of other conditions:

  • Viral exanthemas including measles
  • Streptococcal disease (e.g. scarlet fever, toxic shock syndrome)
  • Staphylococcal disease (e.g. scalded skin syndrome, toxic shock syndrome)
  • Bilateral cervical lymphadenitis
  • Leptospirosis and rickettsial diseases
  • Stevens-Johnson syndrome and Toxic Epidermal Necrolysis
  • Drug reactions including mercury hypersensitivty reaction
  • Juvenile Chronic Arthritis

Q5. What investigations should be performed?

Answer and Interpretation

Echocardiography

The most important investigation to assess for cardiac complications. If no abnormalities on presentation the study should be repeated in 4-6 weeks.

Laboratory tests:

  • Rule out other causes:
    • ASOT, AntiDNAse B, throat swabs, blood cultures
  • Non-specific findings seen in KD include:
    • FBC: normochromic anemia and leukocytosis; thrombocytosis (in the 2nd week)
    • LFT changes and hypoalbuminemia
    • increased CRP and ESR
    • Sterile pyuria of ≥10 WBCs per high-power field

The approach to ‘incomplete’ Kawasaki disease is summarised nicely in this Paucis Verbis card from Academic Life in Emergency Medicine: Kawasaki disease.


Q6. What complications may occur?

Answer and Interpretation

Cardiac complications:

  • Carditis during the febrile phase
    • myocarditis with ST-T changes (25%), pericardial effusions (20-40%), valvular dysfunction (1-2%) and cardiac failure (~5%)
  • Coronary vessel abnormalities (occur in 20% of cases if untreated and <5% if treated; peaks at 2-4 weeks)
    • aneurysm formation may lead to fatalities from thrombosis, rupture or ischemia-related dysrhythmia (usually within 6 weeks of onset, but may occur many years later.

Kawasaki disease is a vasculitis that can potentially affect almost any organ, it is commonly associated with:

  • arthritis
  • keratitis and uveitis
  • diarrhoea, vomiting and gallbladder disease
  • coryza and cough

Q8. What specific treatment is required?

Answer and Interpretation

IV immunoglobulin and aspirin

IV immunoglobulin

  • 2g/kg IV over 10 hours
  • ideally start within 10 days of the onset of the illness
  • a second dose may be given if fevers persist

Aspirin

  • 3-5 mg/kg PO daily for 6-8 weeks (when laboratory parameters have fully normalised)
  • some advise higher doses of aspirin until the patient is afebrile or 48-72 hours, but others argue this offers no benefit in addition to treatment with IV immunoglobulin.

Despite these therapies 2-4% of cases still go on to develop coronary artery abnormalities. Corticosteroids may be considered in refractory cases, although there is little evidence supporting their use.


References

More pediatric perplexity

CLINICAL CASES

Paediatric Perplexity

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.