Kabuki syndrome

Disease Description (Causes and Symptoms)

• Definition summary: An acute febrile vasculitis that occurs in children (especially those aged 5 years or younger) and may cause moderate to large coronary artery (heart) complications. Seasonality (spring and winter) and outbreaks occurring in cycles of several years have been reported.
• Causes and pathophysiology: The exact cause is unknown. In patients with a genetic predisposition, infectious factors (such as bacteria or viruses) or environmental stimuli are presumed to excessively activate the immune system, causing inflammation of medium and small arteries (especially the coronary arteries).
• Major symptoms (clinical findings)
  • Fever lasting 5 days or longer (with no other identifiable cause)
  • Four or more of the following five major findings: nonpurulent bilateral conjunctival injection, mucosal changes of the mouth and pharynx (erythema, strawberry tongue, dryness, cracked lips), changes in the extremities (edema, erythema, desquamation during recovery), rash, cervical lymphadenopathy (>1.5 cm)
  • Other findings: abdominal pain, vomiting, diarrhea, cough, runny nose, elevated liver enzymes, elevated inflammatory markers on blood tests (ESR and CRP), early neutrophilia and late thrombocytosis (2–3 weeks)

Treatment Methods and Precautions

• Standard treatment in the acute phase
  • Intravenous immunoglobulin (IVIG) 2 g/kg as a single intravenous infusion (administered within 10 days of fever onset if possible) — greatly reduces the risk of coronary artery complications.
  • Aspirin: high-dose administration for its anti-inflammatory effect during the acute phase, followed by low-dose administration for its antiplatelet effect during the subacute phase (when there are no coronary artery abnormalities) for 6–8 weeks (e.g., 3–5 mg/kg/day).
• If unresponsive to IVIG (persistent fever)
  • Consider additional IVIG administration or treatment with steroids (such as intravenous methylprednisolone), anti-TNF agents (infliximab), or other treatments, either alone or in combination. Consultation with a specialized pediatric cardiovascular and rheumatology team is necessary.
• Management of coronary artery abnormalities (dilation or aneurysm)
  • Small or moderate: Continue long-term low-dose aspirin and conduct regular follow-up echocardiography.
  • In cases of giant aneurysms (e.g., coronary artery diameter ≥5 mm) or a risk of thrombosis, consider adding anticoagulation (such as low-molecular-weight heparin or warfarin) and work with a cardiologist.
  • If ischemic symptoms (stenosis or occlusion) occur, consider coronary angiography and an interventional procedure (percutaneous angioplasty) or surgery.
• Testing and follow-up
  • In all suspected patients, perform an initial electrocardiogram and echocardiography (coronary artery assessment). Follow up at 1–2 weeks and 4–6 weeks (and thereafter if necessary).
• Lifestyle management and precautions
  • After IVIG administration, postponing live vaccines (e.g., MMR and varicella) for a certain period (generally several months according to guidelines, or 6–11 months depending on the case) is recommended because of possible antibody interference — coordinate the vaccination schedule with a pediatrician.
  • While taking aspirin, immediately consult a medical professional if an acute viral infection (varicella or influenza) occurs, considering the risk of Reye syndrome.
  • If coronary artery abnormalities are present, strenuous physical activity and contact sports should be restricted.
• Risk of complications
  • Myocarditis, pericardial effusion, arrhythmia, coronary artery aneurysm, stenosis, ischemia, myocardial infarction, and others. Treatment can reduce the risk, but coronary artery aneurysms may persist in some patients, requiring long-term follow-up.
• Prognosis summary
  • With appropriate early treatment, the prognosis is generally favorable. The recurrence rate is approximately 1–3%, and the mortality rate is very low (<0.1%). The presence or absence of coronary artery complications is a decisive factor in the long-term prognosis.

Checklist Before an Outpatient Visit (Including Items to Bring and Example Questions)

• Items to bring (recommended)
  • List of currently used medications (including dosage and administration times)
  • Medical history (especially heart disease, allergies, previous IVIG administration, and vaccination records)
  • Records of body temperature and the dates of symptom onset and changes in symptoms (such as the date fever began and the date the rash appeared)
  • Previous test results (copies of echocardiography or blood test results, if available)
  • Exposure history (recent contact with infected people or exposure to an outbreak), travel history
• Items to immediately tell the doctor during an outpatient visit
  • How many days the fever has lasted, whether aspirin is being taken, whether IVIG was previously administered, and whether there is a tendency to bleed (such as bruising or nosebleeds)
  • Whether a live vaccine was recently administered (schedule adjustment is especially necessary after IVIG)
• Example questions (things to prepare and ask the doctor)
  • "What are the possible side effects of this medication (IVIG/aspirin)?"
  • "If a coronary artery abnormality is seen on echocardiography, what will the next testing and treatment plan be?"
  • "How long should live vaccinations be postponed after IVIG administration?"

General Example Questions to Ask the Doctor

• What are the side effects of this medication, and what symptoms should be monitored?
• Based on my child's coronary artery status (echocardiography findings), what is the expected course and what is the schedule for follow-up tests?
• How long will inpatient treatment last, and what should we be careful about at home after discharge?
• How should the schedule for future vaccinations (especially live vaccines) be adjusted?

Disease-Specific Example Questions

• Coronary artery dilation (or an aneurysm) was seen on echocardiography. Depending on its size, what immediate and mid- to long-term treatment plans should I know about?
• If fever persists within 36 hours after administration of IVIG 2 g/kg, please explain the recommended next treatment options (additional IVIG, steroids, infliximab, etc.).

(Note: Diagnosis and treatment vary depending on the individual patient's condition. Consult the attending pediatrician and pediatric cardiology specialist regarding specific prescriptions and follow-up plans.)