Which of the following depths of burn is characterized by destruction of the entire epidermis and dermis with involvement of subcutaneous tissue, appearing charred and leathery with no pain sensation?

Explanation

## Classification of Burns by Depth **Key Point:** Burns are classified by depth of tissue destruction. The classical system uses first, second, and third degree (full-thickness), but a **fourth-degree / subdermal burn** is recognised when destruction extends beyond the dermis into subcutaneous fat, fascia, muscle, or bone. ### Burn Depth Classification Table | Feature | Superficial Partial-Thickness (2nd °) | Deep Partial-Thickness (2nd °) | Full-Thickness (3rd °) | Subdermal / 4th Degree | | --- | --- | --- | --- | --- | | **Depth** | Epidermis + superficial dermis | Epidermis + deep dermis | Entire epidermis + dermis | Epidermis + dermis + subcutaneous tissue (± muscle/bone) | | **Appearance** | Red, blistered, moist | Red/pale, blistered | White/brown, leathery | Charred, leathery, black | | **Pain** | Severe | Moderate | None (nerve ends destroyed) | None (complete nerve destruction) | | **Healing** | 2–3 weeks | 3–8 weeks | Requires grafting | Requires grafting / amputation | **High-Yield:** The stem specifies **destruction of the entire epidermis AND dermis WITH involvement of subcutaneous tissue** — this goes beyond a classical full-thickness (3rd degree) burn, which is limited to the full depth of the dermis. When subcutaneous tissue is involved, the injury is classified as a **subdermal (4th-degree) burn**, characterised by a charred, leathery appearance and complete absence of pain due to total destruction of sensory nerve endings. **Clinical Pearl:** The critical distinguishing feature between full-thickness (3rd degree) and subdermal (4th degree) burns is the **depth of involvement**: full-thickness burns destroy the entire dermis but spare subcutaneous structures, whereas subdermal burns extend into subcutaneous fat and deeper tissues. Both are painless, but the charred/leathery appearance with subcutaneous involvement is the hallmark of the subdermal burn. **Reference:** Modi's Medical Jurisprudence & Toxicology (24th ed.) and Parikh's Textbook of Medical Jurisprudence classify burns extending into subcutaneous tissue as subdermal/fourth-degree burns, distinct from classical full-thickness (third-degree) burns. **Mnemonic:** **"Sub-dermal = Sub-cutaneous involvement + Charred + Painless"** — whenever the stem mentions subcutaneous tissue destruction alongside charring and absent pain, think subdermal (4th degree) burn.