🩺 Rashes · Viral exanthem · Scarlet fever · Kawasaki · EM · HSP · Vesicular · Petechial

Schwartz Clinical Handbook — Chapter 64 · Maculopapular · Vesiculobullous · Petechial/purpuric · Erythema infectiosum · Roseola · Varicella · Meningococcemia · HSP

Select rash morphology (maculopapular, vesicular, petechial, target), distribution (palms/soles, flexural, facial), fever pattern, mucous membrane findings, and systemic symptoms → differentiate viral exanthem, scarlet fever, Kawasaki disease, erythema infectiosum, roseola, varicella, hand‑foot‑mouth, meningococcemia, HSP, and EM/Stevens‑Johnson.
⚠️ Red flags: petechiae/purpura + fever → meningococcemia (IV antibiotics). Vesicles + pneumonia → VZV. Target lesions + mucosal involvement → SJS (urgent dermatology).

📋 Step 1 — Rash morphology & distribution
📌 Diagnostic impressions
📖 Schwartz Ch 64

Select rash type (maculopapular, vesicular, petechial/purpuric, target), distribution (face, trunk, flexural, palms/soles), fever pattern, mucous membrane involvement, and systemic symptoms → differentiate viral exanthem (measles, rubella, roseola, parvovirus), scarlet fever, Kawasaki disease, varicella, hand‑foot‑mouth, HSP, meningococcemia, erythema multiforme / SJS.

✔️ Measles: 3 Cs (cough, coryza, conjunctivitis), Koplik spots, maculopapular head‑to‑toe.
✔️ Scarlet fever: sandpaper rash, strawberry tongue, circumoral pallor, Group A Strep.
✔️ Varicella: vesicles in different stages, centripetal distribution.
✔️ Kawasaki: fever >5d, conjunctivitis, rash, edema, cervical adenopathy.
✔️ Meningococcemia: petechiae/purpura, fever, ill appearance → emergency.
📘 Schwartz pearls (Chapter 64)
• Petechiae + fever → blood culture, empiric ceftriaxone, isolate.
• Kawasaki: IVIG 2 g/kg + aspirin, echocardiogram.
• Erythema infectiosum (parvovirus B19): “slapped cheek”, lacy reticular rash.
• Roseola (HHV‑6): high fever then rash as fever breaks.
• HSP: palpable purpura (buttocks/legs), arthritis, abdominal pain, monitor urinalysis.