Master Vivaan, a 2-year-old male child, born of a non-consanguineous marriage from Bengaluru, Karnataka, presented to the pediatric emergency with high-grade continuous fever for 7 days ($102-104^\circ\text{F}$) unyielding to paracetamol and oral antibiotics, bilateral non-purulent red eyes for 5 days, fiery red cracked lips and strawberry tongue for 4 days, swelling and redness of both hands and feet for 3 days, a red blotchy rash over trunk and diaper area for 3 days, and a painful right neck swelling for 2 days.

HOPI

The history is dated back to 7 days ago when the child acutely developed high-grade fever reaching $103-104^\circ\text{F}$.

• High Continuous Fever (7 Days Duration):
  • Spiking up to $104^\circ\text{F}$ ($40.0^\circ\text{C}$), remittent, unyielding to oral amoxicillin-clavulanate prescribed by a local pediatrician.
  • Child is intensely irritable, inconsolable, and refuses to be put down Points to sterile cerebral vasculitis / aseptic meningitis characteristic of acute Kawasaki disease.
• Bilateral Eye Redness:
  • Appeared on Day 3 of fever. Bilateral, symmetrical injection of the white part of the eyes (bulbar conjunctiva).
  • Completely devoid of purulent discharge, pus, eye mattering, or crusting; eyelids do not stick together in the morning Rules out bacterial or adenovirus conjunctivitis; perilimbal sparing is classic for Kawasaki vasculitis.
• Oral Cavity Changes:
  • Lips became fiery red, dry, severely cracked, and bled on touch.
  • Tongue developed prominent raised red spots resembling the surface of a strawberry (Strawberry tongue) with diffuse pharyngeal erythema.
• Extremity Changes & Inability to Walk:
  • Developed tense, brawny, non-pitting edema and erythema of both palms and soles on Day 5.
  • The child cried when his feet were touched and completely refused to stand or walk.
• Polymorphous Skin Rash:
  • Maculopapular erythematous rash appeared on the trunk and groin.
  • Mother noted intense fiery redness in the diaper area with early sheet-like peeling of skin (perineal desquamation).
• Cervical Swelling:
  • Rapidly developing painful swelling on the right side of the neck for the past 48 hours.
• BCG Scar Reactivation:
  • Mother observed that the old BCG vaccination scar on the left upper arm became swollen, raised, bright red, and crusted over the last 3 days Cross-reactive T-cell response between mycobacterial HSP65 and human endothelial HSP63.
• Negative History:
  • No history of watery purulent rhinorrhea, harsh barking cough, or stridor Rules out measles or viral respiratory infections.
  • No history of vesicular fluid-filled lesions or honey-colored crusts Rules out varicella or staphylococcal scalded skin syndrome.
  • No history of sudden flaccid paralysis, seizures, or vomiting.

Past History

• Born full-term, birth weight 3.2 kg; uneventful neonatal course.
• No history of recurrent wheezing, atopy, or drug allergies.

Family history

• Non-consanguineous marriage.
• Father 34 years, software engineer; Mother 30 years, homemaker; both healthy.
• Elder brother (5 years old) is completely healthy.
• Paternal Grandfather: Had premature myocardial infarction at 52 years of age.

Immunization history

• Received BCG and OPV-0 at birth (healed scar present on left deltoid).
• Fully immunized up to age including Pentavalent, OPV, fIPV, Rotavirus, PCV, and MR-1 at 9 months.

Dietary history

• Consumes a mixed family diet; currently refusing solid foods due to lip fissures and strawberry tongue.

24-Hour Recall Deficit Analysis

$$ \text{Ideal Body Weight (IBW for 2 years, 50th centile WHO)} = 12.2\text{ kg} $$

Nutrient	Expected Intake (ICMR-NIN 2024 for IBW 12.2 kg)	Observed Intake	Deficit	Percentage Deficit
Energy (kcal)	$12.2\text{ kg} \times 83\text{ kcal/kg} = 1012\text{ kcal}$	520 kcal	492 kcal	48.6% Deficit
Protein (g)	$12.2\text{ kg} \times 1.07\text{ g/kg} = 13.0\text{ g}$	6.8 g	6.2 g	47.7% Deficit

Socioeconomic and KAP

• Modified BG Prasad Socioeconomic Class I (Upper Class).
• Parents aware of the urgency of cardiac evaluation due to high fever and eye redness.

Summary of History

Master Vivaan, a 2-year-old male child born of non-consanguineous parentage, presented on Day 7 of illness with high continuous fever ($104^\circ\text{F}$), bilateral non-exudative conjunctivitis, strawberry tongue, indurated erythema of palms and soles, perineal desquamating exanthem, right cervical lymphadenopathy, and BCG scar reactivation, with extreme irritability.

I would like to consider a diagnosis of Complete (Classic) Kawasaki Disease on Day 7 of illness, requiring immediate echocardiographic coronary evaluation and high-dose IVIG therapy.

General head to toe examination

• Behavioral State: Prechtl State 4/5 (Extremely irritable, restless, crying inconsolably, clings to mother).
• Vitals:
  • Heart Rate: 144 beats/minute, regular, bounding volume (tachycardia disproportionate to fever, suggesting myocarditis).
  • Respiratory Rate: 28 breaths/minute, regular.
  • Blood Pressure: $88/54\text{ mmHg}$ ($50^{\text{th}}$ centile, normotensive).
  • Temperature: $39.6^\circ\text{C}$ ($103.3^\circ\text{F}$).
  • Capillary Refill Time: $<2$ seconds; extremities warm.
• Anthropometry:

Parameter	Observed	Expected (50th WHO)	Centile	Inference
Weight	11.8 kg	12.2 kg	$50^{\text{th}}\text{ centile}$	Normal baseline nutrition
Length	86.5 cm	87.0 cm	$50^{\text{th}}\text{ centile}$	Normal Stature
Head Circumference	48.2 cm	48.5 cm	Normal	Age-appropriate

• Comprehensive Evaluation of AHA Principal Criteria:
  1. Bilateral Bulbar Conjunctival Injection: Present bilaterally, glassy red, non-exudative; distinct clear halo around the limbus (perilimbal sparing); no photophobia or discharge.
  2. Oral Cavity Changes: Lips swollen, deep red, with vertical bleeding fissures; Strawberry Tongue with hypertrophied fungiform papillae protruding through a red mucosal surface; diffuse pharyngeal hyperemia; no tonsillar exudate.
  3. Extremity Changes: Tense, brawny, painful non-pitting edema of bilateral palms and soles with fiery erythema; refusal to bear weight.
  4. Polymorphous Exanthem: Diffuse, non-vesicular maculopapular rash over the trunk; prominent confluent erythema in the perineal region with fine superficial desquamation.
  5. Cervical Lymphadenopathy: Solitary, firm, moderately tender right anterior cervical lymph node measuring $2.0 \times 1.5\text{ cm}$; non-fluctuant, overlying skin faintly erythematous.
  6. BCG Scar Reactivation: The $6\text{ mm}$ BCG scar over the left deltoid is distinctly raised, indurated, fiery red, and crowned by a superficial crust.

Systemic Examination

Cardiovascular System (CVS)

• Precordium hyperactive; apex beat in 4th left intercostal space, $0.5\text{ cm}$ lateral to midclavicular line.
• Tachycardia (144 bpm) with Gallop Rhythm ($S_3$ audible at apex) Points to acute Kawasaki myocarditis.
• Grade 2/6 soft systolic murmur heard at apex (transient mitral regurgitation due to papillary muscle inflammation); JVP not raised.

Abdomen

• Symmetrically full, soft; mild right upper quadrant tenderness on deep palpation; liver palpable 2.0 cm below right costal margin, soft; spleen not palpable. (Gallbladder hydrops is a recognized finding).

Respiratory & Central Nervous System

• Clear breath sounds bilaterally. Neurological: Irritable, no neck stiffness, anterior fontanelle closed, cranial nerves intact.

Summary

Master Vivaan, a 2-year-old male child, presents on Day 7 of high continuous fever with all 5 principal AHA criteria: bilateral non-exudative perilimbal-sparing conjunctivitis, cracked lips with strawberry tongue, brawny edema of palms and soles, polymorphous perineal-accentuated exanthem, and unilateral cervical lymphadenopathy ($2.0\text{ cm}$), accompanied by BCG scar reactivation and sinus tachycardia with gallop rhythm (myocarditis).

Final Clinical Diagnosis: Complete (Classic) Kawasaki Disease on Day 7 of illness, complicated by acute myocarditis, requiring emergent high-dose IVIG ($2\text{ g/kg}$) and oral Aspirin therapy to prevent coronary artery aneurysm formation.

Differential Diagnosis

Condition	Points IN FAVOR	Points AGAINST
Kawasaki Disease (Complete)	Fever $\ge 5$ days, 5/5 AHA criteria, BCG scar erythema, extreme irritability, myocarditis gallop	Primary Clinical Diagnosis
Measles (Rubeola)	High fever, conjunctivitis, maculopapular rash, lymphadenopathy	Measles features the "3 Cs" (Cough, Coryza, Conjunctivitis with purulent photophobia), Koplik spots on buccal mucosa, and rash begins behind ears spreading downwards (not perineal)
Systemic JIA (sJIA)	High fever, rash, lymphadenopathy, high inflammatory markers	Fever in sJIA is quotidian (spikes once daily and normalizes); rash is evanescent salmon-pink; sJIA lacks strawberry tongue and BCG reactivation
Scarlet Fever (Group A Strep)	Strawberry tongue, fever, red rash	Scarlet fever rash has sandpaper texture, Pastia lines in flexures, circumoral pallor, and purulent tonsillar exudate; responds dramatically to penicillin
Multisystem Inflammatory Syndrome in Children (MIS-C)	Kawasaki-like phenotype, strawberry tongue, conjunctivitis	MIS-C occurs in older children ($8-12$y), presents with severe vasodilatory shock/hypotension, marked ventricular dysfunction, and positive COVID-19 history
Stevens-Johnson Syndrome (SJS)	Mucosal crusting, conjunctivitis, rash	SJS is precipitated by drugs (NSAIDs, antiepileptics), features targetoid bullous lesions with skin detachment (Nikolsky positive), and severe hemorrhagic mucosal necrosis

Investigation Protocol & Diagnostic Workup

flowchart TD
    A["Child with Fever ≥ 5 Days & ≥ 4 Principal Criteria"] --> B["Stat Transthoracic Echocardiography & ECG"]
    B --> C["Establish Baseline Coronary Diameters & Calculate Z-Scores"]
    C --> D["Stat CBC, ESR, CRP, Platelets, LFT, RFT, Sterile Pyuria Check"]
    D --> E["Immediately Administer IVIG 2 g/kg (Over 10-12 Hours)"]
    E --> F["Co-Administer Oral Aspirin (30-50 mg/kg/day divided Q6H)"]
    F --> G{"Fever Persistent ≥ 36 Hours Post-IVIG?"}
    G -->|Yes: IVIG Resistance| H["Administer 2nd IVIG (2 g/kg) OR Pulse Methylprednisolone OR Infliximab"]
    G -->|No: Defervescence Achieved| I["Switch to Low-Dose Antiplatelet Aspirin (3-5 mg/kg/day) for 6-8 Weeks"]

1. Cardiovascular Evaluation (The Critical Test)

• Transthoracic Echocardiography (Day 7 of Illness):
  • Left Main Coronary Artery (LMCA): Internal lumen diameter $3.6\text{ mm}$ ($Z\text{-score} = +3.2$ $\rightarrow$ Small Coronary Artery Aneurysm; normal $<2.0$).
  • Left Anterior Descending (LAD): Diameter $2.8\text{ mm}$ ($Z\text{-score} = +2.6$ $\rightarrow$ Ectasia/Small Aneurysm).
  • Right Coronary Artery (RCA): Diameter $2.5\text{ mm}$ ($Z\text{-score} = +2.1$).
  • Left Ventricular Ejection Fraction (LVEF): $54\%$ (Mild myocardial systolic dysfunction / myocarditis).
  • Trace pericardial effusion ($2\text{ mm}$ posterior echo-free space).
• 12-Lead ECG: Sinus tachycardia (144 bpm), prolonged PR interval ($0.16\text{ sec}$ $\rightarrow$ 1st degree AV block), flattened T waves in lateral leads (myocardial ischemia/inflammation).

2. Laboratory Markers of Vasculitis

• Complete Blood Count:
  • Hemoglobin: $9.8\text{ g/dL}$ (Normocytic normochromic anemia).
  • White Blood Cell Count: $19,800/\mu\text{L}$ ($78\%$ neutrophils with band forms).
  • Platelet Count: $480,000/\mu\text{L}$ on Day 7 (expected to climb to $>800,000/\mu\text{L}$ in Weeks 2 to 3).
• Inflammatory Markers:
  • ESR: $94\text{ mm/hr}$.
  • CRP: $118\text{ mg/L}$ (Markedly elevated).
• Serum Biochemistry:
  • Serum Albumin: $2.8\text{ g/dL}$ (Hypoalbuminemia reflecting severe capillary leak).
  • Serum Sodium: $132\text{ mEq/L}$ (Hyponatremia $\le 133\text{ mEq/L}$ adds 2 points on Kobayashi score).
  • Liver Enzymes: AST $86\text{ U/L}$, ALT $112\text{ U/L}$ (Transaminitis).
• Urine Routine (Uncentrifuged):
  • Sterile Pyuria: $18-20\text{ WBCs/HPF}$ without bacteria (originates from urethral vasculitis).

Therapeutic Management Protocol (AHA 2017 Guidelines)

1. Primary Immunomodulatory Therapy (Initiated on Day 7)

1. Intravenous Immunoglobulin (IVIG):
   • Dose: $2.0\text{ g/kg}$ administered as a single continuous intravenous infusion over 10 to 12 hours.
   • For this child ($11.8\text{ kg}$): Total dose $= \mathbf{23.6\text{ grams}}$ of IVIG.
   • Mechanism: Rapidly suppresses systemic endothelial inflammation, neutralizes superantigens, downregulates cytokine production, and slashes the risk of coronary artery aneurysms from $25\%$ down to $<3-5\%$.
2. Oral Aspirin (Acetylsalicylic Acid):
   • Anti-Inflammatory Phase: $30\text{ to } 50\text{ mg/kg/day}$ divided into 4 doses (Q6H) orally ($100\text{ mg}$ Q6H) until the child has been afebrile for 48 to 72 hours.
   • Antiplatelet Phase: Once afebrile, switch to low-dose Aspirin at $3\text{ to } 5\text{ mg/kg/day}$ as a single morning dose ($40-50\text{ mg}$ OD).
   • Continue antiplatelet aspirin for 6 to 8 weeks post-onset, or indefinitely if coronary artery aneurysms persist on serial echocardiograms.

2. Monitoring & Follow-Up Protocol

• Repeat echocardiography at 2 weeks and 6 to 8 weeks post-illness onset to monitor for aneurysm progression, regression, or thrombosis.
• Defer all live virus vaccines (Measles, MMR, Varicella) for 11 months following high-dose IVIG.
• Influenza vaccination (inactivated) is mandatory while on long-term aspirin therapy to prevent Reye syndrome.