Paediatrics: Kawasaki disease

Kawasaki disease

Kawasaki disease is the commonest cause of acquired heart disease in children in the UK. It affects 3.4/100,000 children under 5yrs (boys > girls) and in the UK mortality is 3.7%. It is a systemic vasculitic disease with coro-nary arteritis leading to coronary artery aneurysms as the most important complication (20–30%). Other complications include coronary thrombo-sis, myocardial infarction, and dysrrhythmias.

Diagnostic criteria

The diagnosis can be made in children with fever (>38.5*C) present for at least 5 days, without other explanation, in the presence of 4 of the 5 following criteria. Criteria may not be present at the same time (history is important) and misery is a very common feature.

•   Bilateral congestion of the ocular conjunctivae (94%): non-purulent.

•   Changes of the lips and oral cavity with at least one of the following: dryness, erythema, fissuring of lips (70%); strawberry tongue (71%); diffuse erythema of oral and pharyngeal mucosa without discrete lesions (70%).

•   Changes of the extremities with at least one of the following: erythema of palms and soles (80%); indurative oedema (67%); periungual desquamation of fingers and toes (29%).

•   Polymorphous exanthem (92%).

•   Non-suppurative cervical lymphadenopathy >1.5cm (42%).

Note: The percentage values indicate the proportion of patients manifest-ing this clinical sign within the first 10 days after onset of fever.

Differential diagnosis

The differential diagnosis for Kawasaki disease includes the following:

•   Streptococcal and staphylococcal toxin-mediated diseases

•   Adenovirus and other viral infections (enterovirus, measles)

•   Drug reactions or Stevens–Johnson syndrome

•   Leptospirosis

•   Yersinia pseudotuberculosis infection

•   Rickettsial infection

•   Reiter’s syndrome

·  IBD

•   Post-infectious immune complex disease (e.g. post-meningococcaemia)

•   Sarcoidosis

Associated features

In addition to the diagnostic criteria of Kawasaki disease, the other fea-tures of the condition include the following.

•   Renal: urethritis with sterile pyuria.

Musculoskeletal: arthralgia and arthritis (35% of patients).

• CNS: aseptic meningitis with mild CSF pleocytosis and normal CSF glucose and protein; sensorineural hearing loss (transient high frequency loss or permanent loss).

• GI: diarrhoea and vomiting; hydrops of the gall bladder with or without obstructive jaundice.

• Cardiac: congestive heart failure, myocarditis, pericardial effusion, arrhythmias, mitral insufficiency, acute myocardial infarction (up to 73%) within 1yr of disease.

·Coronary aneurysms: incidence of coronary artery aneurysms varies (15–25% in untreated patients) and resolution varies with age at onset and size and shape of aneurysm.

Investigations

• Haematology: leucocytosis with left shift common in acute phase; thrombocytosis peaks in the 3rd to 4th week; normocytic, normochromic anaemia present early and persists until inflammatory process begins to subside; reticulocyte count low.

• Coagulation: increased coagulability, platelet turnover, and depleted fibrinolysis.

• Urine: mononuclear cells with cytoplasmic inclusions are abundant in the urine early in the disease. These cells are not detected by dipstick methods for ‘WBC’, which only detect polymorphs.

• Acute phase reactants: elevated ESR persists beyond the acute febrile period and gradually returns to normal over 1–2mths. CRP may also be elevated.

• Biochemistry: elevated liver transaminases; hypoalbuminaemia.

• Immunology: marked activation of circulating monocyte/macrophages; B cell activation elevated immunoglobulin production; T cell lymphopenia.

• Cardiology: ECG usually normal, but strain, ischaemia, and/or infarct can be present.

• Echocardiography: aneurysms may first be seen from 7–21 days post-onset of fever.

Treatment

• High dose IV immunoglobulin is the treatment of choice. 2g/kg over 12hr as a single infusion. Consider repeat dose after 48hr if no deferevescence.

• Aspirin: 30—50mg/kg/day (divided qds) reducing to 3–5mg/kg as fever resolves.

• The role of steroids and novel biological therapies is not clear.

Follow-up is very important for cardiac review.