A 35-year-old man is brought to the hospital after being trapped in a house fire. On examination, the skin shows a leathery, dark brown appearance with a contracted appearance and loss of elasticity. Which finding best distinguishes this from a scald injury of the same surface area?

Explanation

## Deep Thermal Burns vs. Scalds: Eschar Characteristics ### Pathophysiology of Eschar Formation **Key Point:** The eschar (burnt tissue) in deep thermal burns has distinct physical properties that differentiate it from scald injuries, even when both are severe. | Feature | Deep Burn (Dry Heat) | Deep Scald | |---------|---------------------|------------| | **Eschar appearance** | Leathery, dark brown/black, rigid | Softer, less rigid, more exudative | | **Contractility** | Marked contraction, inelastic | Variable, may retain some elasticity | | **Fluid exudation** | Minimal (coagulation necrosis) | Significant (colliquative necrosis) | | **Char depth** | Deep charring of dermis/subcutis | Superficial charring | | **Underlying tissue** | Desiccation, coagulation | Liquefactive changes | | **Margin appearance** | Sharp demarcation | Gradual transition | ### Mechanism: Why Burns Produce Rigid Eschar **High-Yield:** Dry heat (flame, contact) causes **coagulation necrosis** — proteins denature and cross-link, producing a rigid, leathery, non-exudative eschar. Scalds cause **colliquative necrosis** — tissue liquefies, producing significant serous exudation and a softer eschar. ### Clinical Pearl **Clinical Pearl:** The rigid, contracted eschar with minimal fluid exudation is a hallmark of deep flame burns and is forensically significant. This appearance reflects the mechanism of injury — sustained high-temperature contact causing complete protein denaturation. ### Mnemonic **Mnemonic:** **COAG-BURN** = Coagulation necrosis → Rigid, Rigid eschar, Absent exudation; **COLIQ-SCALD** = Colliquative necrosis → Liquid exudation, Soft eschar.