## Diagnosis: Measles ### Clinical Presentation This case presents the classic triad of measles prodrome followed by the characteristic rash and pathognomonic oral findings. **Key Point:** Koplik's spots (small white spots with red halos on the buccal mucosa) are pathognomonic for measles and appear 2–3 days before the rash, during the prodromal phase. ### Prodromal Phase (3–4 days) The "3 Cs" of measles prodrome: - **Cough** (often severe, "barking") - **Coryza** (nasal discharge) - **Conjunctivitis** (photophobia common) - High fever (often >39°C) ### Rash Characteristics - **Onset:** Appears 3–4 days after fever onset, begins on the **hairline and forehead** - **Progression:** Cephalocaudal (head → trunk → limbs over 3–4 days) - **Morphology:** Maculopapular, non-blanching, may coalesce - **Peak fever:** Often coincides with rash appearance ("fever with rash") **High-Yield:** The rash of measles is **maculopapular and non-blanching**, distinguishing it from other viral exanthems. ### Koplik's Spots - Appear on **buccal mucosa opposite molars** - Small white spots (1–2 mm) with red halo - Appear during prodrome, fade as rash develops - Highly specific for measles **Clinical Pearl:** Koplik's spots are transient and fade as the rash appears, so they may be missed if the child is examined after rash onset. ### Risk Factors in This Case - Unvaccinated child (no MMR vaccine) - Rural setting (lower vaccination coverage) - Age 4 years (typical age for measles in unvaccinated populations) **Mnemonic: KOPLIK** — **K**oplik spots, **O**ral (buccal mucosa), **P**rodrome (3 Cs), **L**ow vaccination, **I**nfectious (highly contagious), **K**eratitis (corneal involvement possible) [cite:Park 26e Ch 23]
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