Synonyms: Kawasaki’s disease, Kawasaki/Kawasaki’s syndrome, mucocutaneous lymph node syndrome, infantile periarteritis nodosa, infantile polyarteritis nodosa.

This is an idiopathic self-limiting systemic vasculitis that most often affects children in the age range 6 months to 5 years. It predominantly affects children of Asian origin, particularly Japanese and Chinese populations (possibly because of genetic susceptibility), but there is an appreciable worldwide incidence.
It was first described in 1967 by Tomisaku Kawasaki, a Japanese paediatrician. It is thought to be a relatively new disease, not having been described until the 1950s.

It was originally thought to be a troubling but benign illness, but it was later realised that deaths and significant morbidity occur through its major complication of coronary artery aneurysm formation.
It has taken over from rheumatic fever as the most common cause of acquired childhood heart disease in the developed world. Prior to its delineation, cases had been described and classified on histological grounds as infantile polyarteritis/periarteritis nodosa. Early diagnosis and early treatment are now strongly advocated to reduce complications

Its characteristic features are outlined below:

Classical features of Kawasaki disease

Fever lasting ?5 days.
Marked irritability of the child.
Erythema, swelling and desquamation affecting the skin of the extremities.
Bilateral conjunctivitis.
Rash.
Inflammation of the lips, mouth and/or tongue.
Cervical lymphadenopathy.

Epidemiology
The highest annual incidence is thought to occur in Japan at ~120-180 cases per 100,000 children aged under 5 years. The incidence appears to be rising year on year in Japan.

In Europe, recent surveys have demonstrated a peak annual incidence among children of Asian descent of 90 cases per 100,000 children aged under 5 years.

Analysis of hospital statistics in England has shown an incidence of 8 per 100,000 of children aged under 5 years. The higher incidence in North East Asians persists after migration to countries with low incidence.

The incidence does appear to be variable, with local epidemic outbreaks occurring in winter and spring on a three-year cycle, suggesting an infective aetiology

In the USA, the approximate annual race-specific incidence per 100,000 children younger than 5 years ranges from 9.1 for children of white descent to 32.5 for children of Asian and Pacific island descent. The Caucasian incidence is thought to be roughly about a tenth of the Pacific Asian incidence, overall.

Risk factors

It is much more common in Asian populations (see above).
It is more common in boys, with a M:F ratio of 1.5:1
In the USA/Europe, peak incidence is in children aged 18-24 months.
Japanese peak incidence is 6-12 months.
80% of cases occur in children aged <5 years.
The condition occurs only rarely in children aged <6 months or >5 years (although cases have, rarely, been observed in adolescents and adults).

Aetiology and pathophysiology
These remain a mystery, although a combination of an infective trigger and genetic susceptibility seems likely (research is focusing on the role of the expression of HLA-Bw22J2 antigen, a component of the major histocompatibility complex, found predominantly in Japanese populations).
The condition is caused by an autoimmune-mediated systemic vasculitis that affects small- and medium-sized arteries.

Presentation

Consider the diagnosis of Kawasaki disease in a child who is irritable with a persistent fever. The classic clinical features of Kawasaki disease may not all be present. The rash may mimic common infections (eg, measles, rubella, parvovirus and scarlet fever) and may also resemble erythema multiforme.

Symptoms

The usual presenting feature is a fever of abrupt onset. The child tends to be very irritable and unwell when febrile, often out of proportion to the severity of the fever. Most consider that the fever must have been present for at least five days for Kawasaki disease to be diagnosed; however, experienced clinicians may make the diagnosis earlier in its course, if there are other classical features.
As well as fever, there must be at least four of the following to fit the diagnostic criteria (or echocardiographic evidence of coronary artery aneurysms):

Inflammation and irritation of the lips, mouth and/or tongue.
Erythema, oedema and/or desquamation of the extremities.
Bilateral dry conjunctivitis.
Widespread non-vesicular rash.
Cervical lymphadenopathy >1.5 cm in size.

Other possible features include lethargy, symptoms of urethritis, diarrhoea, vomiting, abdominal pain, myalgia, arthralgia and arthritis. A Chinese survey found that there appears to be an appreciable incidence of atypical or ‘incomplete’ Kawasaki disease and that such cases appear to have a high prevalence of coronary artery lesions. The presence of perianal desquamation may be a useful indicator of the likelihood of such ‘incomplete’ cases.

Signs
The lips typically become erythematous or fissured, along with inflamed oral mucosa and the presence of a ‘strawberry tongue’ – so-called because it is extremely erythematous with prominent papillae.

The rash is described as a polymorphic exanthem and comes on within 3-5 days of the onset of fever. It usually begins with nonspecific erythema of the soles, palms, and perineum, spreading to involve the trunk and the rest of the extremities. It is often itchy and variable in appearance, but is never vesiculo-bullous.
It is usually markedly red and may appear macular, morbilliform, papular, scarlatiniform, urticarial, akin to erythema multiforme or be made up of very many tiny micropustules.
Desquamation may affect the perineal area, moving to the fingers and then the toes. In the extremities, it usually begins in the periungual region.

The hands and feet often become red and swollen and tender before desquamation begins.

The conjunctivitis is never associated with exudate, is bilateral and tends to spare the perilimbal area.

Cervical lymphadenopathy is usually unilateral, non-tender and affects the anterior cervical chain.

Cardiovascular signs are usually nonspecific. Tachycardia, a hyperdynamic precordium, a gallop rhythm or a flow murmur may be present; however, these signs are not unusual in febrile patients without Kawasaki disease. There are occasionally signs of valvular incompetence.

Other possible signs include:

Neck stiffness due to aseptic meningitis.
Hepatomegaly and jaundice.
Phases of the illness.

The disease typically follows three phases, as outlined in the table below:

The phases of Kawasaki disease

Time from fever onset
Predominant features
Acute 1-2 weeks
Highly febrile.
Very irritable.
Toxic-appearing.
Oral changes rapidly following.
Oedema and erythema of feet.
Rash especially common in the perineal area.

Subacute 2-8 weeks
Gradual improvement.
The fever settles.
Desquamation of the perineum, palms, soles.
Arthritis, arthralgia.
Thrombocytosis.
Coronary artery aneurysms.
Myocardial infarction.

Convalescent Months to years
Resolution of remaining symptoms.
Laboratory values return to normal.
Aneurysms may resolve or persist.
Beau’s lines.
Cardiac dysfunction and myocardial infarction may still occur.

Subsidiary features of the disease.

Cardiovascular – pancarditis, aortic or mitral incompetence.
Gastrointestinal – hydrops of gallbladder, jaundice, diarrhoea.
Blood – mild anaemia.
Renal – sterile pyuria, mild proteinuria.
CNS – aseptic meningitis.
Musculoskeletal – arthritis, arthralgia.
Others – anterior uveitis, BCG-site inflammation.

Do request- Diff Diagnosis, MANAGEMENT,THEREPY,COMPLICATIONS,PROGNOSIS- if needed.

Dr G Mohan.