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Kawasaki Disease (Mucocutaneous Lymph Node Syndrome)

Kawasaki Disease (KD) is an acute multi-system immune-mediated vasculitis of unknown etiology which usually presents in infancy and early childhood. 85% of children are less than 5 years of age. KD is the leading cause of acquired heart disease in children in the USA. In untreated KD patients, the incidence of coronary artery aneurysm ranges from 15-25%. Myocardial infarction from thrombotic occlusion of the coronary arteries is the principle cause of death. KD is more common in patients of Asian descent. The prognosis depends on the extent of the cardiac involvement.

Pathogenesis
The etiology of KD is unknown. KD involves small to medium-sized arteries, including the coronary arteries; the extent of the coronary artery involvement is the critical that determines morbidity and mortality. Investigators propose that mediators such as tumor necrosis factor (TNF), interleukin (IL)-1B, interferon (INF) and IL-6 produced by activated T-cells and macrophages promote vascular injury. The earliest pathological change reported in the vessel wall is subendothelial accumulation of T-cells, mononuclear cells, macrophages and monocytes.

Clinical presentation
KD is divided into three phases.

  • The acute phase begins with onset of high fever without an apparent source and can last for 1-2 weeks. Acute myocardial infarction may occur during the acute phase due to perivasculitis and vasculitis.
  • In the subacute phase, which may last for 2-4 weeks, the fever subsides. Desquamation of the skin and coronary artery aneurysms appear in this phase. The platelet count might rise above 106 per mm3 in this phase.
  • During the convalescent phase, the symptoms resolve and the sedimentation returns to normal, usually within 6-8 weeks following onset of the illness.

Making the Diagnosis

  • Fever of unknown origin lasting for 3 days or more, in addition to fourof the following signs:
  • Bilateral conjunctival injection without exudates.
  • Changes in mucous membranes such as injected or fissured lips, strawberry tongue.
  • Extremity change including erythema of palms or soles and edema of the hands or the feet.
  • Polymorphous exanthema.
  • Acute cervical lymphadenopathy (and isolated node > 1.5 cm in diameter).
  • Tachycardia and gallop rhythm (secondary to myocarditis) may occur.
  • Pericardial effusion, aortic regurgitation, and mitral regurgitation may be seen.
  • High leukocyte count with left shift is commonly noted.
  • Thrombocytosis may be present after a few days of illness.
  • Increased acute phase reactants such as ESR and C-reactive protein are usual.
  • Urinalysis might demonstrate white blood cells in the absence of infection (sterile pyuria).
  • The child is usually very irritable and a CSF pleocytosis may be present.
  • EKG shows mild abnormalities consistent with myocarditis such as arrhythmias, prolonged PR and QT intervals and nonspecific ST segment changes.
  • Echo can show pericardial effusion, LV dilation, and/or decreased systolic function. Follow up echo should be done in 3-5 weeks. The need for further echocardiograms is determined the presence or absence of coronary involvement.
  • Coronary angiography should not be done in the acute phase but may be needed later on to evaluate coronary lumen anatomy and blood flow.
  • Stress test may be needed to detect myocardial ischemia.

Management
Early detection of KD and prompt treatment reduce mortality below 1%. Baseline echocardiogram should be performed as soon as the diagnosis is made. IV immunoglobulin (IVIG) and high dose aspirin are the mainstays of therapy. A single dose of IVIG results in resolution of the clinical symptoms in most patients. IVIG given early can reduce the incidence of coronary artery abnormalities.

Conventional therapy for KD also includes aspirin which has anti-inflammatory and anti-thrombotic properties. The risk of coronary artery thrombosis is greatest after the acute phase. If there is no coronary artery involvement, aspirin should be continued until the acute phase reactants return to normal. If there are coronary aneurysms, long term aspirin and warfarin are needed.

American Academy of Pediatrics. Diagnosis, Treatment, and Long-Term Management of Kawasaki Disease: A Statement for Health Professionals from the Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease, Council on Cardiovascular Disease in the Young, American Heart Association. Pediatrics 114 (6) December 2004, pp. 1708-1733 (doi:10.1542/peds.2004-2182)