Kawasaki Disease

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Chapter 160 Kawasaki Disease

Kawasaki disease (KD), formerly known as mucocutaneous lymph node syndrome and infantile polyarteritis nodosa, is an acute febrile illness of childhood seen worldwide in all populations, with the highest incidence occurring in children of Asian background. KD is a vasculitis with a predilection for the coronary arteries, and approximately 20-25% of untreated patients experience coronary artery abnormalities, including aneurysms. KD is the leading cause of acquired heart disease in children in most developed countries, including the USA and Japan.

Etiology

The cause of KD remains unknown, but certain epidemiologic and clinical features support an infectious origin. These features include the young age group affected, epidemics with wavelike geographic spread of illness, the self-limited nature of the acute febrile illness, and the combination of clinical features fever, rash, enanthem, conjunctival injection, and cervical lymphadenopathy. Further evidence of an infectious trigger includes the infrequent occurrence of the illness in infants younger than 3 mo, likely the result of maternal antibodies, and the virtual absence of cases in adults, likely the result of prior exposures with subsequent immunity. Nonetheless, it is unusual to have multiple cases present at the same time within a family or daycare center. A genetic role in the pathogenesis of KD seems likely, as evidenced by the higher risk of KD in Asian children regardless of country of residence and in siblings and children of individuals with a history of KD. Furthermore, genome-wide association studies, including sibling pair analyses, have identified susceptibility loci.

A KD-associated antigen has been described in cytoplasmic inclusion bodies within ciliated bronchial epithelial cells from acute fatal cases. These inclusions appear consistent with viral protein aggregates and support the hypothesis of a respiratory portal of entry of the KD agent. However, no single infectious etiologic agent has been successfully identified, despite a comprehensive search.

Some of the features of KD, such as fever and diffuse rash, suggest superantigen activity, similar to that seen in toxin-mediated diseases like staphylococcal toxic shock syndrome. Studies of polyclonal activation of T cells, characteristic of superantigen-mediated processes, have yielded conflicting results in patients with KD. Similarly, the role of regulatory T cells, chemokines, and Toll-like receptors in KD has been studied, with inconclusive results. During the subacute phase of illness, levels of all immunoglobulins (Igs) are elevated, suggesting that a vigorous antibody response occurs. As in other forms of vasculitis, it is likely that a common environmental trigger leads to the phenotype of KD in genetically predisposed individuals.

Clinical Manifestations

Fever is characteristically high (≥101°F), unremitting, and unresponsive to antibiotics. The duration of fever without treatment is generally 1-2 wk but may persist for 3-4 wk. In addition to fever, the five principal clinical criteria of KD are: bilateral nonexudative bulbar conjunctival injection with limbal sparing; erythema of the oral and pharyngeal mucosa with strawberry tongue and dry, cracked lips; edema and erythema of the hands and feet; rash of various forms (maculopapular, erythema multiforme, or scarlatiniform) with accentuation in the groin area; and nonsuppurative cervical lymphadenopathy, usually unilateral, with node size >1.5 cm (Table 160-1; Figs. 160-1 to 160-4). Perineal desquamation is common in the acute phase. Periungual desquamation of the fingers and toes begins 1-3 wk after the onset of illness and may progress to involve the entire hand and foot (Fig. 160-5).

Table 160-1 CLINICAL AND LABORATORY FEATURES OF KAWASAKI DISEASE

EPIDEMIOLOGIC CASE DEFINITION (CLASSIC CLINICAL CRITERIA)*

OTHER CLINICAL AND LABORATORY FINDINGS

LABORATORY FINDINGS IN ACUTE KAWASAKI DISEASE

* Patients with fever at least 5 days and <4 principal criteria can be diagnosed with Kawasaki disease when coronary artery abnormalities are detected by two-dimensional echocardiography or angiography.

In the presence of ≥4 principal criteria, Kawasaki disease diagnosis can be made on day 4 of illness. Experienced clinicians who have treated many patients with Kawasaki disease may establish diagnosis before day 4.

See differential diagnosis (Table 160-2).

§ Some infants present with thrombocytopenia and disseminated intravascular coagulation.

From Newburger JW, Takahashi M, Gerber MA, et al: Diagnosis, treatment, and long-term management of Kawasaki disease, Pediatrics 114:1708–1733, 2004.

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Figure 160-2 Strawberry tongue in mucocutaneous lymph node syndrome (Kawasaki disease).

(Courtesy of Tomisaku Kawasaki, MD.) (From Hurwitz S: Clinical pediatric dermatology, ed 2, Philadelphia, 1993, WB Saunders.)

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Figure 160-3 Congestion of bulbar conjunctiva in a patient with mucocutaneous lymph node syndrome (Kawasaki disease).

(Courtesy of Tomisaku Kawasaki, MD.) (From Hurwitz S: Clinical pediatric dermatology, ed 2, Philadelphia, 1993, WB Saunders.)