Paediatrics · Hard
This case is fictional and exists for study. It describes no real patient.
1 years · female
An 18-month-old girl is brought to the emergency department by her mother with a 6-day history of high-grade fever up to 39.5°C that has been poorly responsive to paracetamol and ibuprofen. Her mother reports that she has become increasingly irritable, refuses to walk, and is taking minimal fluids. On examination, the child is miserable and pyrexial. She has bilateral non-exudative conjunctival injection, dry, cracked, erythematous lips, and a strawberry tongue. A diffuse polymorphous maculopapular rash is visible over her trunk. Her palms and soles are markedly erythematous with non-pitting oedema of the hands and feet. A solitary, left-sided anterior cervical lymph node is palpable, measuring 1.8 cm. Respiratory and abdominal examinations are otherwise unremarkable.
Vital signs
- HR
- 152 bpm
- BP
- 92/56 mmHg
- RR
- 32/min
- Temp
- 39.2 °C
- SpO₂
- 98%
Examination findings
- Bilateral non-purulent conjunctival injection
- Red, cracked lips and strawberry tongue
- Erythema and oedema of hands and feet
- Solitary left cervical lymph node (1.8 cm)
- Polymorphous trunk rash
Investigations
| C-reactive protein (CRP) | 118 mg/L | reference: < 5 |
| Erythrocyte sedimentation rate (ESR) | 82 mm/hr | reference: < 15 |
| White blood cell count (WBC) | 19.4 10^9/L | reference: 6.0-17.5 |
| Platelet count | 540 10^9/L | reference: 150-450 |
| Haemoglobin | 10.1 g/dL | reference: 10.5-13.5 |
Question 1 of 3
What is the single most likely diagnosis?
Kawasaki disease is diagnosed clinically in a child with fever for at least 5 days plus at least 4 of the 5 principal features: bilateral non-exudative conjunctivitis, oral mucosal changes (strawberry tongue, red/cracked lips), extremity changes (erythema/oedema of hands/feet), polymorphous rash, and cervical lymphadenopathy (>1.5 cm, usually unilateral). Measles typically presents with prominent cough, coryza, Koplik spots, and a rash spreading from head down. Scarlet fever features tonsillar exudates and a fine, sandpaper-like rash following group A streptococcal pharyngitis. Systemic JIA presents with quotidian (daily spiking) fevers lasting at least 2 weeks, arthritis, and transient rash.
Teaching point: Kawasaki disease is a clinical diagnosis established by persistent fever for 5 or more days plus at least 4 characteristic mucosal, cutaneous, or lymphatic criteria.
Question 2 of 3
Which of the following is the most appropriate next investigation to perform?
A baseline transthoracic echocardiogram is mandatory upon diagnosis or strong suspicion of Kawasaki disease to detect baseline coronary artery abnormalities (such as ectasia or aneurysms), pericardial effusion, or ventricular dysfunction. Lumbar puncture is not indicated without specific signs of meningitis or neurological deficit. ASO titers evaluate recent streptococcal infection (relevant to scarlet fever or rheumatic fever), which is not the primary diagnostic priority here. Bone marrow aspiration is used for haematologic malignancies and is unnecessary.
Teaching point: A baseline echocardiogram should be performed as soon as Kawasaki disease is suspected to evaluate for coronary artery abnormalities and cardiac function.
Question 3 of 3
What is the single most appropriate initial treatment for this patient?
Standard initial treatment for Kawasaki disease is high-dose intravenous immunoglobulin (IVIG, 2 g/kg as a single infusion) combined with high-dose aspirin. Administering IVIG within the first 10 days of fever onset markedly reduces the risk of coronary artery aneurysm formation from approximately 25% to under 5%. Antibiotics such as ceftriaxone or amoxicillin have no role in treating Kawasaki disease unless a co-existing bacterial infection is documented. Corticosteroids are reserved for high-risk patients or IVIG-resistant cases as adjunctive therapy rather than initial monotherapy.
Teaching point: Prompt administration of IVIG and high-dose aspirin within 10 days of fever onset significantly decreases the risk of coronary artery aneurysms in Kawasaki disease.
Key learning points
- Kawasaki disease is a paediatric systemic vasculitis diagnosed clinically by 5 or more days of high fever and characteristic mucocutaneous and nodal findings.
- Coronary artery aneurysms are the most significant complication of Kawasaki disease, making baseline and follow-up echocardiograms essential.
- Early administration of single-dose IVIG (2 g/kg) and high-dose aspirin within 10 days of illness onset drastically lowers the risk of cardiac sequelae.
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