**Question:** True regarding thermal injury is A/E -

A. Burns are a significant source of morbidity and mortality globally.
B. First-degree burns are limited to the epidermis and are usually self-limiting.
C. Second-degree burns involve both the epidermis and dermis and can result in scarring.
D. Third-degree burns involve all layers of the skin and underlying structures, including nerves and blood vessels.

**Correct Answer:**

**Core Concept:** Thermal injury refers to damage caused by heat, cold, or radiation to tissues, leading to inflammation, cellular damage, and potential scarring. The severity of thermal injury is classified into four grades based on the extent of skin involvement.

**Why the Correct Answer is Right:**

D. Third-degree burns (Full-thickness burns) are the most severe type of thermal injury, resulting in damage to all layers of the skin, including the epidermis, dermis, and subcutaneous tissue. Additionally, third-degree burns often involve underlying nerves, blood vessels, and other structures. This can lead to significant morbidity and mortality, as well as long-term functional and cosmetic impairments.

**Why Each Wrong Option is Incorrect:**

A. Burns are a significant source of morbidity and mortality globally is partially correct, as burns do contribute to global health issues. However, this option does not explain the depth and severity of thermal injury, which is best described by the correct answer.

B. Burns affecting only the epidermis (first-degree burns) are usually self-limiting, meaning they typically heal without intervention within a few days to a week. Although first-degree burns are less severe than third-degree burns, they are not self-limiting and do not involve all skin layers.

C. Second-degree burns (partial-thickness burns) affect both the epidermis and dermis, causing inflammation and cellular damage, but do not involve all skin layers or underlying structures like nerves and blood vessels.

**Clinical Pearls:**

1. Thermal injury is a common cause of injury and disease worldwide, particularly in developing countries with limited resources for burn care.
2. Early recognition of burn severity is crucial for proper management and patient outcomes. Thermal injury is typically classified into four grades (A, B, C, and D) based on the depth of tissue damage:

- Grade A: Superficial dermal burns (first-degree burns) present as redness and swelling, with minimal pain and blistering. They usually heal within a few days to a week without scarring.
- Grade B: Partial-thickness burns (second-degree burns) involve the epidermis and dermis, causing inflammation and cellular damage, but do not involve deeper structures like nerves and blood vessels. They may result in scarring and contractures if not properly managed.
- Grade C: Full-thickness burns (third-degree burns) involve the epidermis, dermis, and subcutaneous tissue, causing destruction of skin appendages, nerves, and blood vessels. These burns result in extensive tissue damage, rendering the affected area