Kawasaki disease (KD; also known as mucocutaneous lymph node syndrome) is an immune-mediated disorder of unknown etiology that occurs in genetically predisposed children leading to endothelial cell injury and vasculitis of mainly medium-sized arteries (predilection for coronary arteries). Small arterioles, larger arteries, capillaries, and veins are affected to a lesser extent. KD occurs in all ethnic groups; however, incidence is highest in East Asia and in children of Asian descent. Clinical and epidemiologic features strongly support an infectious etiology. About 80% of patients are <5 years of age (peak: between 18 and 24 months); about 90% of patients are <8 years. There is no specific test for KD; diagnosis is based on clinical criteria summarized in Table 12.1. Other findings include extreme irritability, aseptic meningitis (50%), urethritis (sterile pyuria, 70%), hepatic dysfunction (40%), hydrops of gallbladder, diarrhea, vomiting, abdominal pain, arthritis, or arthralgia (knees, ankles, hips), uveitis, pneumonitis, testicular swelling, peripheral gangrene, erythema, or induration at bacille Calmette-Guérin inoculation site.
Diagnosis is established clinically by:
Clinical phases (after onset of illness):
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Figure 12.2 ▪ Features of Kawasaki Disease (KD).
(A) Temperature curve in a typical untreated case of KD. With the administration of intravenous immune globulin on the seventh day of hospitalization (diagnosis of KD entertained), temperature returned to normal. (B) Red lips with fissuring, giving the appearance of red lipstick. (C) Nonexudative conjunctivitis. (D) Red strawberry tongue. (E) Erythema of the palm with desquamation of fingers, seen on the eighth day of illness (patient’s hand against mother’s hand). (F) Erythema of the soles. (G) Perineal desquamation seen in this 18-month-old infant with KD on the fourth day of illness. (H) Cervical adenopathy. (I) Desquamation of the fingers on the 12th day of illness. (Photo contributor: Binita R. Shah, MD.)
Figure 12.3 ▪ Kawasaki Disease (KD).
(A) Frontal projection shows cardiomegaly and pulmonary vascular congestion in a child with KD presenting with evidence of myocarditis. During acute phase of KD, pericardium, myocardium, endocardium, valves including coronary arteries may be involved. (B) Sonogram of the right upper quadrant shows thick-wall, dilated gallbladder. Acute acalculous hydrops occurs in about 15% of patients during the first 2 weeks of the illness. (Photo contributor: Rafael Rivera, MD.)
Figure 12.4 ▪ Incomplete Kawasaki Disease.
Red lips (A), erythematous maculopapular rash (B), and perineal desquamation (C; present since third day of illness) in an infant presenting with fever (9 days’ duration) not responding to either antibiotic (given for otitis media) or antipyretic therapy. This infant lacked eye and extremity findings and cervical adenopathy. (Photo contributor: Binita R. Shah, MD.)
Incomplete Kawasaki disease refers to KD with incomplete clinical manifestations and occurs more commonly in young infants than in older children. Incomplete KD is the preferred term over atypical KD as these patients do not have any atypical features, but they lack sufficient signs to fulfill the diagnosis of KD. Laboratory findings are similar in both classic and incomplete KD.
Obtain CBC (normal to elevated WBC count with a predominance of polymorphonuclear leukocytes and normocytic anemia), ESR and C-reactive protein (usually elevated), liver enzymes (elevated with hypoalbuminemia), and urinalysis (sterile pyuria and proteinuria). If clinically indicated, perform a lumbar puncture; cerebrospinal fluid will show mild pleocytosis with normal glucose and usually normal protein. Obtain chest radiograph to look for cardiomegaly and an ECG for evidence of myocarditis, pericarditis, or arrhythmias. Admit patients with clinical diagnosis of KD or incomplete KD for continuous cardiac monitoring and treatment that includes intravenous immune globulin (IVIG; given as a single dose over 8–12 hours) and anti-inflammatory dose aspirin (given until patient is afebrile for at least 3–4 days) followed by antithrombotic dose (given until platelet count, ESR and ECHO are normal). Low-dose aspirin therapy is continued indefinitely if a coronary artery abnormality is detected. Consult cardiology on admission. Patients need a 2-dimensional ECHO at baseline and during subsequent follow-ups.
Figure 12.5 ▪ Incomplete Kawasaki Disease (KD).
(A, B) Desquamation of the hand and foot are shown in 2 different infants (not suspected of having KD) who remained extremely irritable and highly febrile and not responding to IV antibiotics given for a clinical diagnosis of sepsis (all cultures negative). Prolonged fever followed by peripheral desquamation is among the most common signs of incomplete KD. ECHO in both these infants showed coronary artery dilation. (Photo contributor: Binita R. Shah, MD.)
KD is a leading cause of acquired heart disease in children.
Administration of IVIG in the acute phase (within 10 days of onset of fever) significantly reduces the prevalence of coronary artery dilation and aneurysms.
Perineal desquamation seen within the first week of illness in a highly febrile infant or child is an important early diagnostic clue.
Significant thrombocytosis (platelet count up to 1 million) occurs in the second week of illness.
Diagnosis is often delayed in young infants (incomplete KD) and in older children leading to higher prevalence of cardiovascular complications.
Consider incomplete KD in any infant with prolonged and unexplained fever lasting for >5 days even in the absence of other clinical criteria. Prolonged fever may be the sole manifestation of KD in infants.
Leukopenia and a normal ESR in an infant or child with fever, rash, and red eyes does not suggest a laboratory profile compatible with KD (suggests a viral infection).
Acute adenoviral infection shares many features of KD. Purulent conjunctivitis and exudative pharyngitis suggests adenoviral infection, whereas perineal desquamation, extremity changes, and sterile pyuria suggest KD.
Exudative conjunctivitis, Koplik spots, cough, and rash starting on face behind the ears, becoming confluent, and fading with a brownish hue suggest measles. KD rash is most prominent on the trunk and extremities and fades abruptly without residua. Perineal desquamation is also not seen in measles.
Figure 12.6 ▪ Coronary Artery Aneurysms (CAAs) in Kawasaki Disease (KD).
The coronary angiogram shows multiple giant CAAs along the left coronary artery in an infant with a prolonged and refractory course of KD. He had ectasia of all coronary arteries during acute illness. He presented to the ED with inconsolable crying episodes 6 weeks post discharge. ECG showed ST elevation in lateral chest leads and ECHO was suggestive of CAA. (Photo contributor: Shyam Sathanandam, MD.)
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