## Anatomical Distribution of Impetigo **Key Point:** The face and exposed areas (particularly around the nose and mouth) are the most common sites of impetigo in children, accounting for 70–80% of cases. ### Why the Face and Exposed Areas? 1. **Increased trauma:** Minor cuts, abrasions, and insect bites on exposed skin provide portals of entry 2. **Higher bacterial colonization:** The nasal vestibule and perioral region are common sites of S. aureus colonization 3. **Moisture and maceration:** Frequent contact with hands and saliva increases bacterial proliferation 4. **Sun exposure:** UV exposure may impair local immune function ### Frequency by Site | Site | Frequency | Reason | |------|-----------|--------| | **Face (nose, mouth, chin)** | 70–80% | High trauma, colonization, moisture | | **Exposed extremities** | 15–20% | Minor trauma, insect bites | | **Trunk** | 5–10% | Covered, less trauma | | **Scalp/hairline** | <5% | Less common; more common in bullous impetigo | **High-Yield:** The perinasal and perioral regions are particularly susceptible because S. aureus naturally colonizes the anterior nares in 20–30% of the population, making these areas high-risk for autoinoculation. **Clinical Pearl:** Impetigo often spreads in a centrifugal pattern from the initial site, following areas of trauma and contact. Lesions on the face are more likely to spread to the neck and upper extremities. **Mnemonic:** **FACE** = **F**requent trauma, **A**nterior nares colonization, **C**ontact/moisture, **E**xposed to environment.
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.