Clinical presentation and diagnostic criteria
The disease runs a strictly cyclic course. The acute febrile stage takes the first 1–2 weeks and is accompanied by severe malaise: the child becomes extremely irritable.
The diagnosis is made clinically, as there are no specific tests. The baseline criterion is persistent fever (38.5–40 °C) lasting for at least 4–5 days (on average about 11 days). Against the background of the fever, involvement of five key areas unfolds:
- Eyes: bilateral conjunctival injection, sometimes involving the sclerae.
- Oral cavity and lips: diffuse hyperemia of the oral and pharyngeal mucosa. The lips become dry, edematous, and cracked (cheilitis). A classic "raspberry" (strawberry) tongue with hypertrorophied papillae develops.
- Peripheral extremities: in the acute phase, the hands and feet become red, and a dense (indurative) edema appears. In the 2nd–3rd week (subacute phase), the skin on the fingers begins to desquamate characteristically.
- Skin: a diffuse polymorphic rash erupts on the trunk and extremities.
- Lymphatic system: cervical lymphadenopathy. Most often, a single node enlarges asymmetrically (more than 1.5 cm in diameter) without signs of suppurative melting.
In addition, non-specific manifestations may occur: joint syndrome (arthritis, arthralgia), dyspepsia (vomiting, diarrhea), abdominal pain, transient hepatomegaly, aseptic meningitis, pulmonary infiltrates, and testicular edema.
Cardiovascular complications
Involvement of the cardiovascular system determines the prognosis of the entire disease. The changes are divided into two groups:
- Reversible (pancarditis): inflammation can affect all layers of the heart (pericardium, myocardium, endocardium), valves, and conduction system. These phenomena generally regress completely upon recovery.
- Prognostically unfavorable: formation of coronary artery aneurysms. The process starts from the 7th–10th day of the illness and can last up to 6 weeks.
According to echocardiography (EchoCG), aneurysms are classified by size (small — up to 5 mm, medium — 5–8 mm, giant — more than 8 mm) and by morphology (spheroid/saccular and fusiform). Giant aneurysms pose the greatest threat due to the high risk of thrombosis and stenosis distal to the dilation.
Laboratory and instrumental diagnostics
Since there are no pathognomonic markers, the physician relies on a set of non-specific shifts.
- Acute stage: neutrophil leukocytosis and hypochromic anemia are detected in the blood. Signs of other organ involvement include transient cytolytic syndrome (elevated transaminases), hyperbilirubinemia, and sterile leukocyturia (a consequence of urethritis).
- Subacute stage (from the 2nd week): there is a sharp surge in acute-phase markers (ESR and CRP). The most prominent sign is progressive thrombocytosis, reaching 1,000,000/µL and higher.
ECG and EchoCG are indicated for all patients as a baseline screening. Stress tests, CT/MSCT, and invasive coronary angiography are used according to indications for precise visualization of the vascular bed.
Outcomes and therapeutic management
The convalescence (recovery) stage takes from 6 to 10 weeks — this is how long it takes for symptoms to completely disappear and laboratory tests to normalize. An interesting delayed retrospective marker of a past syndrome is the appearance of transverse grooves on the nail plates several months later.
The main goal of treatment is to prevent coronary bed involvement. To achieve this, it is critically important to start pathogenetic therapy within the first 10 days from disease onset. The drug of choice at this stage is intravenous immunoglobulin (IVIG).
The "RED" patient rule: Red high fever, Red eyes (conjunctivitis), Red raspberry tongue, Red rash, and Red swollen palms/soles.
Class and exam questions
Because the disease is based not on a bacterial infection, but on a systemic immune-mediated necrotizing vasculitis. The fever here is refractory to antibiotics.
The disease is based not on a bacterial infection, but on a systemic immune-mediated necrotizing vasculitis. The fever is persistent and completely refractory to antibiotics.
What causes leukocyturia in such patients?
Sterile leukocyturia occurs due to specific urethritis, which is one of the manifestations of systemic mucosal involvement.
When do aneurysms appear and how to detect them?
Coronary aneurysms begin to form from the 7th–10th day of fever onset. Echocardiography (EchoCG) serves as the primary method for their detection and monitoring.
What else to study on this topic
- Pathogenetic mechanisms of aneurysm formation in medium-sized arteries
- Intravenous immunoglobulin (IVIG) administration protocols and criteria for resistance
- Differential diagnosis with measles, scarlet fever, and systemic juvenile idiopathic arthritis
- Indications for invasive coronary angiography in children
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