🌡️📋 Chapter 40: Fever and Rash

Nelson's Pediatric Symptom-Based Diagnosis | Viral exanthems · Meningococcemia · Kawasaki disease · Rocky Mountain spotted fever · Toxic shock syndrome · Stevens-Johnson syndrome · Vesicular rashes · Petechiae

🔍 Fever and Rash in Children: Key Concepts

📊 Maculopapular exanthems
Measles (Koplik spots, cough, coryza, conjunctivitis), rubella (lymphadenopathy), roseola (HHV-6, fever then rash), fifth disease (slapped cheeks, lacy rash).
🦠 Petechial/purpuric (RED FLAG)
Meningococcemia (fever, ill-appearing, petechiae → purpura), RMSF (palms/soles, centripetal), HSP (palpable purpura lower extremities), viral (enterovirus, EBV).
👶 Vesiculobullous
Chickenpox (stages, pruritic, centripetal), HSV, hand-foot-mouth (enterovirus), SSSS (Nikolsky, periorificial, infants).
🩸 Kawasaki Disease
≥5 days fever + 4/5: conjunctivitis, oral changes, rash, extremity changes, cervical lymphadenopathy. Coronary aneurysms risk. IVIG + aspirin.
⚠️ Toxic Shock Syndrome
Diffuse erythroderma, fever, hypotension, multisystem involvement. S. aureus (TSST-1) or GAS. Requires clindamycin + vancomycin/penicillin + IVIG.
💊 Stevens-Johnson/TEN
Drug-induced (carbamazepine, phenytoin, sulfa, NSAIDs), mucosal erosions, target lesions, epidermal detachment. Life-threatening. Discontinue drug, supportive care.

💡 Key takeaway: Identify life-threatening causes: meningococcemia, RMSF, TSS, Kawasaki, SJS/TEN, SSSS. Petechiae with fever in a toxic child = meningococcemia until proven otherwise. Classic viral exanthems can be diagnosed by pattern recognition.

🩺 Clinical Approach to Fever and Rash: Life-Threatening First

🔹 Step 1: Assess for toxicity and petechiae/purpura
• Ill-appearing, toxic → immediate resuscitation, blood cultures, IV antibiotics (ceftriaxone + vancomycin) for possible meningococcemia.
• Petechiae above nipple line after vomiting/coughing: usually benign.
• Palpable purpura → vasculitis (HSP) or septic emboli.
🔹 Step 2: Identify rash morphology and distribution
• Maculopapular: measles, rubella, roseola, fifth disease, EBV, enterovirus.
• Vesicular: varicella, HSV, enterovirus (hand-foot-mouth), rickettsialpox.
• Diffuse erythroderma: scarlet fever (sandpaper, Pastia lines), TSS (sunburn, mucous membranes), Kawasaki (polymorphous, perineal desquamation).
• Palms/soles petechiae: RMSF, meningococcemia, endocarditis.
🔹 Step 3: Look for diagnostic clusters
• Kawasaki: ≥5d fever + conjunctivitis + oral changes + rash + edema/erythema hands/feet + cervical lymphadenopathy.
• TSS: fever, hypotension, desquamation, multisystem, strawberry tongue.
• SJS/TEN: target lesions/erosions, mucosal involvement, drug exposure 1-3 weeks prior.
🔹 Step 4: Laboratory and diagnostic aids
• CBC, CRP, blood cultures if toxic or petechial.
• LP if meningeal signs.
• Echocardiogram for suspected Kawasaki (coronary arteries).
• Skin biopsy for suspected vasculitis or SJS/TEN.
• PCR for HSV, VZV, enterovirus, measles.
🔹 Step 5: Empiric treatment when indicated
• Suspected meningococcemia: ceftriaxone or cefotaxime.
• RMSF: doxycycline (even in young children).
• TSS: clindamycin + vancomycin/penicillin + IVIG.
• Kawasaki: IVIG 2g/kg + high-dose aspirin.
• SJS/TEN: stop drug, supportive care (burn unit), IVIG if severe.