Pediatric Exanthems, Kawasaki Disease & Inflammatory Syndromes
Comprehensive emergency protocol for pediatric dermatologic emergencies and systemic inflammatory vasculitides. Features the diagnostic differentiation of classic pediatric exanthems (Measles, Rubella, Roseola, Fifth Disease, Scarlet Fever), the strict 10-day IVIG treatment window in Kawasaki disease to prevent coronary artery aneurysms, the tetrad of Henoch-Schönlein purpura (HSP), and the resuscitation of meningococcemia and purpura fulminans.
Resuscitation Quick Actions • First 2 Minutes
Kawasaki 10-Day Window
Fever >= 5 days + CRASH criteria: Administer IVIG 2 g/kg over 10-12h + Aspirin within 10 days to prevent coronary aneurysms
Meningococcemia Rule
Petechiae/purpura with fever/tachycardia: Stat Ceftriaxone 100 mg/kg IV (max 2g) immediately before any diagnostic imaging or LP
HSP/IgA Vasculitis Tetrad
Palpable purpura on buttocks/lower legs + Arthralgias + Abdominal pain + Renal disease; platelets are completely normal
SSSS vs SJS/TEN
SSSS (Staphylococcal Scalded Skin): Nikolsky positive, mucous membranes SPARED. SJS/TEN: Severe mucous membrane sloughing
Roseola Classic History
High fever for 3-4 days that abruptly breaks, followed immediately by pink maculopapular rash starting on trunk
Kawasaki Disease (CRASH and Burn Criteria)
Fever >= 5 days (Burn) PLUS >= 4 of: Conjunctivitis (bilateral non-exudative), Rash (polymorphous), Adenopathy (cervical >1.5 cm), Strawberry tongue/oral erythema, Hands and feet erythema/edema (CRASH). Treat with IVIG (2 g/kg) + High-Dose Aspirin to prevent coronary artery aneurysms.
Multisystem Inflammatory Syndrome in Children (MIS-C)
Post-COVID-19 hyperinflammatory state with multi-organ involvement (cardiac, GI, hematologic), shock, and markedly elevated inflammatory markers.
Bottom-Line Clinical Pearl
In Kawasaki disease (fever >= 5 days plus 4 of 5 CRASH criteria: Conjunctivitis, Rash, Adenopathy, Strawberry tongue, Hand/foot erythema), administer high-dose IVIG (2 g/kg) and Aspirin within the 10-day golden window to reduce the incidence of catastrophic coronary artery aneurysms from 25% to under 4%. In acute purpuric or petechial rashes with shock (meningococcemia), never delay immediate IV Ceftriaxone (100 mg/kg) for blood cultures or lumbar puncture.
Viral and bacterial exanthems in children represent distinct immunological and pathophysiological processes. Accurate clinical differentiation prevents inappropriate antibiotic prescribing and identifies contagious life threats:
| Infectious Exanthem | Etiologic Pathogen | Prodrome & Classic Enanthem | Cutaneous Morphology & Evolution |
|---|---|---|---|
| Measles (Rubeola/First Disease) | Measles Virus (Paramyxovirus, negative-sense RNA). Highly contagious airborne transmission. | High fever, malaise, and the 3 Cs: Cough, Coryza, Conjunctivitis (with photophobia). Koplik Spots: Pathognomonic tiny, bluish-white pinpoint granules on an erythematous base on the buccal mucosa opposite lower molars (appear 1-2 days before rash). | Confluent erythematous maculopapular rash that begins on hairline and behind ears, spreading downward (cephalocaudal) over face, trunk, and extremities, coalescing into generalized erythema. Clears in order of appearance with brownish staining and fine desquamation. |
| Rubella (German Measles/Third Disease) | Rubella Virus (Togavirus). Teratogenic: causes Congenital Rubella Syndrome (cataracts, deafness, PDA). | Mild low-grade fever, prominent postauricular, suboccipital, and posterior cervical lymphadenopathy. Forchheimer Spots: Tiny rose-red macules or petechiae on the soft palate and uvula. | Discrete, light pink maculopapular rash starting on face and spreading rapidly downward. Does not coalesce; fades by day 3 ('3-day measles'). |
| Roseola Infantum (Exanthem Subitum/Sixth Disease) | Human Herpesvirus 6 (HHV-6) or HHV-7. Affects infants aged 6 to 18 months. | Sudden, high, unremitting fever (39–40.5°C/102–105°F) lasting 3 to 5 days in a relatively well-appearing child (high risk of febrile seizures!). | THE CLASSIC TIMING: The fever ABRUPTLY DROPS TO NORMAL (DEFERVESCENCE), and within hours a rose-pink maculopapular rash appears first on the trunk and neck, later spreading to proximal extremities. Resolves within 24–48 hours. |
| Erythema Infectiosum (Fifth Disease) | Human Parvovirus B19. Infects and destroys erythroid progenitor cells in bone marrow. | Mild low-grade fever, headache, pharyngitis. Complications: severe transient Aplastic Crisis in sickle cell disease/spherocytosis, and Hydrops Fetalis in seronegative pregnant females. | Three-Stage Rash: 1. 'Slapped-Cheek' Sign: Bright confluent erythematous facial rash with marked circumoral pallor. 2. One to four days later: Symmetric, erythematous, reticular 'lace-like' macular rash on trunk and extremities. 3. Waxes and wanes for weeks, exacerbated by heat, sunlight, or exercise. |
| Scarlet Fever (Scarlatina) | Group A Streptococcus (Streptococcus pyogenes) producing pyrogenic exotoxins (SpeA, SpeB, SpeC). | Fever, sore throat, tonsillar exudates, cervical lymphadenopathy. Strawberry Tongue: White coating with hyperemic papillae (White Strawberry Tongue) shedding after 2 days to reveal beefy red tongue (Red Strawberry Tongue). | Finely papular erythematous rash with a coarse 'sandpaper' texture. Accentuated in skin creases (axillae, antecubital fossae, groin) as non-blanching petechial lines (Pastia's Lines). Followed by coarse desquamation of hands and feet 1-3 weeks later. |
Kawasaki disease is an acute, self-limiting necrotizing vasculitis of medium-sized muscular arteries with a profound predilection for the coronary arterial circulation. It is the leading cause of acquired pediatric heart disease in developed countries. Untreated children have a 20-25% incidence of coronary artery dilation, giant aneurysms (> 8 mm), thrombosis, and myocardial infarction:
| Diagnostic Component | Clinical Criteria (Fever >= 5 Days + >= 4 of 5 CRASH) | Pathognomonic Manifestations & Timing |
|---|---|---|
| MANDATORY REQUIREMENT | Fever Lasting >= 5 Consecutive Days | High, unremitting remittent fever (typically > 38.5–40°C) unresponsive to standard antipyretics and broad-spectrum antibiotics. |
| C: Conjunctivitis | Bilateral Conjunctival Injection | Painless, bulbar, non-exudative injection with striking perilimbal (corneal) sparing. Absence of purulent discharge distinguishes it from bacterial conjunctivitis. |
| R: Rash | Polymorphous Cutaneous Exanthem | Erythematous, generalized maculopapular, scarlatiniform, or erythema multiforme-like rash. Prominent accentuation in the perineal/diaper area with early desquamation. Non-vesicular (vesicles rule out Kawasaki!). |
| A: Adenopathy | Cervical Lymphadenopathy | Typically unilateral cervical lymph node > 1.5 cm diameter, firm, non-tender, non-suppurative. |
| S: Strawberry Tongue/Oral | Oropharyngeal Changes | Erythema, swelling, and vertical cracking/bleeding of the lips; diffuse mucosal erythema of the oropharynx; classic strawberry tongue. |
| H: Hand & Foot Extremity Changes | Peripheral Extremity Manifestations | Acute Phase: Intense erythema of the palms and soles with firm, brawny, painful non-pitting edema of hands and feet. Convalescent Phase (Weeks 2-3): Sheet-like periungual desquamation starting under the fingernails and toenails. |
| Emergency Treatment Protocol | 1. Intravenous Immunoglobulin (IVIG): 2.0 grams/kg IV administered as a single continuous infusion over 10 to 12 hours. 2. High-Dose Aspirin (ASA): 80 to 100 mg/kg/day PO divided every 6 hours until afebrile for 48 hours, then drop to low-dose Aspirin (3 to 5 mg/kg/day) for 6 to 8 weeks. | THE 10-DAY GOLDEN RULE: Administering IVIG within the first 10 days of fever onset reduces the rate of coronary artery aneurysms from 25% to < 3-4%. In infants < 6 months, clinical signs are often incomplete; maintain a low threshold for cardiology echocardiography. |
| Vasculitic Syndrome | Pathophysiology & Presentation | Emergency Complications & Management |
|---|---|---|
| Henoch-Schönlein Purpura (HSP/IgA Vasculitis) | Small-vessel leukocytoclastic vasculitis mediated by IgA immune complex deposition in skin, joints, gastrointestinal tract, and renal glomeruli. Most common systemic vasculitis of childhood (peak age 3-10 years). The Classic Tetrad: 1. Palpable Purpura: Non-blanching, elevated erythematous papules and purpura distributed symmetrically over dependent areas (buttocks, thighs, and posterior legs). 2. Arthralgias/Arthritis: Oligoarticular swelling of knees and ankles (non-deforming). 3. Abdominal Pain: Colicky, postprandial periumbilical pain. 4. Renal Disease: Microscopic hematuria, proteinuria, hypertension. | EMERGENCY GI COMPLICATION: Bowel wall edema and submucosal hemorrhage act as a lead point for Ileo-Ileal Intussusception (distinct from typical ileocolic intussusception; ultrasound is mandatory for severe pain or bloody stool). Platelet Count Pearl: Platelets and coagulation profile are COMPLETELY NORMAL (distinguishes HSP from ITP, TTP, and meningococcemia). Supportive care with NSAIDs; systemic corticosteroids (Prednisone 1-2 mg/kg/day) reserved for severe GI pain or nephritis. |
| Meningococcemia & Purpura Fulminans | Fulminant bacteremia caused by Neisseria meningitidis. Massive circulating endotoxin (lipooligosaccharide) triggers catastrophic endothelial injury, microvascular thrombosis, and diffuse intravascular coagulation. - Sudden high fever, tachycardia, profound lethargy - Petechiae that coalesce within hours into large, dark, purple, ecchymotic purpura with central necrosis - Peripheral gangrene and ischemic digits - Waterhouse-Friderichsen Syndrome: Bilateral adrenal gland hemorrhage causing acute fatal adrenal crisis and refractory vasoplegic shock. | IMMEDIATE ANTIMICROBIAL RESUSCITATION: Administer Ceftriaxone 100 mg/kg IV (max 2.0g) immediately. Do NOT delay antibiotic administration for CT scan, lumbar puncture, or transfer. Resuscitate with balanced crystalloid boluses and early norepinephrine infusion for septic shock. |
Kawasaki Disease: The 10-Day Golden Window for Coronary Protection
Kawasaki disease is a time-critical clinical diagnosis; there is no definitive confirmatory laboratory test. The primary goal of emergency management is the prevention of coronary artery aneurysms, which form when transmural inflammation weakens the media of the coronary arterial walls. Intravenous Immunoglobulin (IVIG 2 g/kg single infusion) MUST be initiated within the first 10 days of fever onset to provide maximal myocardial protection. If a child presents with prolonged unexplained fever >= 5 days accompanied by mucosal inflammation, unilateral cervical adenopathy, or red hands and feet, never dismiss the presentation as a routine viral syndrome. Obtain an urgent pediatric cardiology consultation for formal echocardiography and admit immediately for IVIG and high-dose aspirin therapy.
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