Kawasaki disease: Clinical sciences

Kawasaki disease, or KD, previously known as mucocutaneous lymph node syndrome, is a vasculitis of unknown etiology that affects medium-sized arteries. Kawasaki disease is the leading cause of acquired heart disease in children in developed countries, and is primarily seen in children under the age of 5. This febrile illness can result in multi-organ dysfunction; however, the presence of coronary artery lesions determines its morbidity and mortality.

Now, if your pediatric patient presents with a chief concern suggesting Kawasaki disease, first perform an ABCDE assessment to determine if they are unstable or stable. If unstable, stabilize their airway, breathing, and circulation. Next, obtain IV access and consider starting IV fluids. Finally, begin continuous vital sign monitoring, including heart rate, blood pressure, and pulse oximetry; and, if needed, don’t forget to provide supplemental oxygen.

Now, here’s a clinical pearl! Kawasaki disease shock syndrome, or KDSS, is a rare but potentially life-threatening complication of KD. It presents with hypotension, shock, and multi-organ failure. Because KDSS is associated with decreased peripheral resistance and reduced cardiac contractility, affected patients require fluid resuscitation and intravenous vasopressors such as epinephrine, along with IV immunoglobulins, which are essential to treat this type of shock.

Okay, let’s go back and take a look at stable patients. First, obtain a focused history and physical examination, and order labs, including a CMP, CBC, ESR, CRP, liver function tests, and a urinalysis. Patients or their caregivers typically describe an abrupt onset of a high, spiking fever lasting for at least 5 days with profound irritability. Some patients report joint pain, while others have abdominal pain, which is related to gallbladder hydrops.

As far as the physical exam goes, you’ll usually notice a unilateral, enlarged, nontender cervical lymph node, as well as a bilateral nonexudative conjunctival injection. Oropharyngeal findings include cracked, red lips and a swollen, red tongue with enlarged papillae, also called a strawberry tongue. Patients also typically develop a widespread rash and painful swelling of the hands or feet.

Laboratory results usually reveal elevated ESR and CRP because Kawasaki disease causes significant systemic inflammation. In fact, if inflammatory markers are normal, Kawasaki disease is unlikely, and you should consider the possibility of another underlying cause. Additionally, some individuals could present with elevated transaminases and gamma-glutamyl transferase, as well as leukocytosis, anemia, and hypoalbuminemia. After the seventh day of fever, some individuals could develop thrombocytosis. Finally, the urinalysis may reveal sterile pyuria, with 10 or more white blood cells per high-powered field.

These findings should lead you to suspect Kawasaki disease, so your next step is to assess your patient using the classic Kawasaki disease criteria. The first criterion is the presence of a fever for at least 5 days. Additional criteria include 5 clinical features. The first one includes oropharyngeal findings, such as erythema and cracking of the lips, a strawberry tongue, or oropharyngeal mucosal erythema. Next is bilateral nonexudative conjunctivitis, which is limited to the bulbar conjunctivae. The third feature is a rash, which is typically maculopapular, but could appear as diffuse erythroderma or erythema multiforme. The fourth one is erythema and edema of the hands and feet during the initial phase of the illness, or periungual desquamation of the hands and feet after two weeks of illness. The final and less commonly seen feature is unilateral cervical lymph node enlargement of more than 1.5 centimeters.

If your patient has had a fever for 5 or more days, with 4 or more of these clinical features, diagnose classic Kawasaki disease.

Now, here’s a high-yield fact! You can also make a diagnosis of classic Kawasaki disease if your patient has only 4 days of fever and 4 or more clinical features, if one of those features is redness and swelling of the hands and feet!

Now, once you make the diagnosis, proceed with treatment. Administer a single infusion of high-dose intravenous immunoglobulin, and begin high-dose aspirin. Additionally, obtain a cardiology consultation to evaluate and treat any cardiac complications, which can include myocarditis, pericarditis, and coronary artery aneurysms.

Here’s a clinical pearl! A single dose of intravenous immunoglobulin leads to rapid clinical improvement for most children and reduces the risk of coronary artery aneurysm. However, if the fever persists for 48 hours after the first dose, you can give a second dose of intravenous immunoglobulin. Alternatively, you can consider giving corticosteroids to patients whose fever doesn’t resolve after intravenous immunoglobulin treatment.