Kawasaki Disease Quiz

Kawasaki Disease: Practice Guide for Exam-Style Questions

Kawasaki disease (KD) is an acute febrile vasculitis of childhood that primarily affects medium-sized arteries, most notably the coronary arteries. Recognizing its classic and incomplete presentations is critical for timely treatment to prevent long-term cardiac complications. This guide focuses on high-yield concepts for exams.

Core Diagnostic Criteria: CRASH and Burn

A helpful mnemonic for the principal clinical criteria is CRASH and Burn. Diagnosis requires a fever lasting at least 5 days (“Burn”) plus at least four of the following five features:

• Conjunctivitis: Bilateral, non-exudative, bulbar conjunctival injection.
• Rash: Polymorphous (maculopapular, morbilliform, or targetoid), typically on the trunk and extremities.
• Adenopathy: Cervical lymphadenopathy, usually unilateral and >1.5 cm.
• Strawberry tongue: Oral mucosal changes, including erythema, fissured lips, and prominent lingual papillae.
• Hands and feet changes: Erythema and edema of the palms and soles, followed by periungual desquamation (peeling) in the subacute phase.

Understanding the Three Phases of Illness

Kawasaki disease progresses through distinct phases, each with characteristic findings. The acute phase (weeks 1-2) is marked by high fever and the CRASH symptoms. The subacute phase (weeks 2-4) sees fever resolution, but desquamation, arthritis, and thrombocytosis emerge. The convalescent phase (weeks 4-8) is when clinical signs resolve, but lab values may still be abnormal.

The Critical Role of Echocardiography

Echocardiography is the cornerstone of monitoring in KD. Its primary purpose is to detect and track coronary artery abnormalities, including dilation and aneurysms. A baseline echocardiogram is performed at diagnosis, followed by repeat studies at 2 weeks and 6-8 weeks to assess for changes.

First-Line Treatment: IVIG and Aspirin

Prompt treatment is crucial to reduce the risk of coronary artery aneurysms from ~25% to less than 5%. The standard of care is a single infusion of high-dose intravenous immunoglobulin (IVIG) combined with high-dose aspirin for its anti-inflammatory effects. Once the fever subsides, aspirin is tapered to a low, anti-platelet dose.

Differentiating from Look-Alike Conditions

Many pediatric illnesses can mimic Kawasaki disease, making careful evaluation essential. Questions often test the ability to distinguish KD from other conditions that cause fever and rash.

• Scarlet Fever: Also has a strawberry tongue and rash, but the rash is typically sandpaper-like (scarlatiniform) and is associated with a preceding streptococcal infection.
• Measles: Features the “3 Cs” (cough, coryza, conjunctivitis) and Koplik spots, which are absent in KD.
• Adenovirus: Can cause high fever, pharyngitis, and bilateral non-exudative conjunctivitis, but extremity changes and significant lab abnormalities are less common.
• Stevens-Johnson Syndrome (SJS): Involves severe mucosal ulceration and targetoid lesions, which are more severe than the changes seen in KD.
• Toxic Shock Syndrome: Presents with hypotension and multi-organ dysfunction, which are not typical of uncomplicated KD.

Key Takeaways for Rapid Review

• Diagnosis is Clinical: Rely on the “CRASH and Burn” criteria; there is no single diagnostic test.
• Cardiac Complications are Key: The most serious complication is coronary artery aneurysm, which can lead to thrombosis or myocardial infarction.
• IVIG is Lifesaving: Administering high-dose IVIG within the first 10 days of illness is the most effective intervention.
• Lab Hallmark: Marked thrombocytosis (high platelet count) is a characteristic finding in the subacute phase.
• Live Vaccines Deferred: Defer MMR and varicella vaccines for 11 months after IVIG administration due to interference from the antibodies.

This content provides a study framework for understanding Kawasaki disease for educational and exam preparation purposes. It is not a substitute for professional medical advice, diagnosis, or treatment.