In non-bullous impetigo, which layer of the epidermis is primarily affected, and what is the characteristic appearance of the crust?

Explanation

## Non-Bullous Impetigo: Pathology and Clinical Features **Key Point:** Non-bullous impetigo is a superficial infection of the **stratum corneum and upper epidermis**, characterized by a pathognomonic **honey-colored (golden) crust**. ### Pathological Features 1. **Site of infection:** Stratum corneum and superficial epidermis 2. **Mechanism:** Direct invasion by *Staphylococcus aureus* and/or *Streptococcus pyogenes* 3. **Inflammatory response:** Neutrophilic infiltrate with minimal acantholysis (unlike bullous impetigo) 4. **Crust formation:** Dried serum, pus, and cellular debris ### Clinical Characteristics of Non-Bullous Impetigo | Feature | Description | |---------|-------------| | **Prevalence** | ~70% of impetigo cases | | **Onset** | Often on areas of minor trauma (insect bites, scratches) | | **Lesion morphology** | Pustules → erosions → crusts | | **Crust appearance** | Honey-colored, golden, or amber | | **Size** | Usually <1 cm, but may coalesce | | **Healing** | Without scarring | | **Causative organisms** | *S. aureus* (most common), *S. pyogenes* | **High-Yield:** The **honey-colored crust** is the clinical hallmark of non-bullous impetigo and is a frequently tested feature. **Mnemonic:** **HONEY** = **H**oney-colored crust in **O**rdinary (non-bullous) **N**on-scarring **E**pidemial **Y**east-free infection (bacterial, not fungal). **Clinical Pearl:** Non-bullous impetigo is more common in tropical and subtropical climates (including India) and in children aged 2–6 years. It spreads rapidly through direct contact and minor skin trauma.