A 28-year-old woman is brought to the emergency department 2 hours after a house fire. She has erythematous, blistered skin over her anterior chest, abdomen, and bilateral forearms. The affected areas are painful to touch and blanch with pressure. The surrounding skin shows areas of deep red discoloration without blistering. On examination, hair on the affected areas is singed but not completely burnt off. What is the depth classification of the primary burn injury on her chest and abdomen?

Explanation

## Burn Depth Classification **Key Point:** Burn depth is classified into four grades based on the layers of skin and underlying tissues involved, with specific clinical features distinguishing each grade. ### Clinical Features of This Case The patient presents with: - **Erythema and blistering** — indicates fluid accumulation in the dermal-epidermal plane - **Pain on touch** — suggests intact sensory nerve endings in the dermis - **Blanching with pressure** — indicates viable capillaries and intact microcirculation - **Singed but not burnt-off hair** — suggests epidermal involvement without complete destruction These findings are pathognomonic for **superficial partial-thickness (second-degree) burn**, which involves the epidermis and superficial dermis. ### Burn Depth Classification Table | Grade | Depth | Clinical Features | Pain | Blanching | Healing | | --- | --- | --- | --- | --- | --- | | **Superficial Partial (2°)** | Epidermis + superficial dermis | Blisters, erythema, moist | Yes (severe) | Yes | 7–21 days, minimal scarring | | **Deep Partial (2°)** | Epidermis + deep dermis | Pale, leathery, few blisters | Reduced | Sluggish | >3 weeks, significant scarring | | **Full-thickness (3°)** | All skin layers | Charred, leathery, white/brown | No | No | Requires grafting, severe scarring | | **Subdermal (4°)** | Extends to muscle/bone | Charring of deeper tissues | No | No | Requires grafting, amputation risk | **High-Yield:** The **presence of pain and blanching** is the most reliable bedside indicator of partial-thickness burns; their **absence** suggests full-thickness injury. **Clinical Pearl:** Blistering is a hallmark of partial-thickness burns because the blister fluid represents plasma that has leaked into the dermal-epidermal junction. In full-thickness burns, the entire dermis is coagulated and does not blister. **Mnemonic: "SBPD"** — **S**uperficial (blisters, severe pain, blanches), **B**leeds when debrided, **P**artial thickness, **D**ermis involved. ### Why This Is Superficial Partial-Thickness and Not Deep Partial Deep partial-thickness burns would show: - Pale or mottled appearance (not erythematous) - Reduced or absent pain sensation - Sluggish or absent blanching - Leathery texture - Minimal blistering The **prominent blistering and severe pain** in this case rule out deep partial-thickness injury. [cite:Park 26e Ch 18]