Which of the following is a sign of full thickness burn?

A full thickness burn, also known as a third-degree burn, is characterized by the destruction of both the epidermis and dermis layers of the skin, affecting underlying tissues. The key feature that distinguishes full thickness burns is the skin's appearance, which is dry and leathery. This occurs because the burn has damaged nerve endings, and as a result, these burns may not be painful in the area directly affected, even though surrounding areas may still have pain due to lesser degrees of burns.

This dry and leathery texture is a direct indication of the extent of tissue damage. Unlike other types of burns that exhibit redness and swelling, pain and blisters, or minor discoloration, a full thickness burn's distinctive look is crucial for identifying its severity and guiding appropriate treatment measures.

The other options represent characteristics more typical of superficial or partial thickness burns. For instance, redness and swelling are signs of inflammation associated with less severe burns, while pain and blisters indicate that the dermis is still intact to some degree, allowing for nerve sensation. Minor discoloration also suggests minor injury rather than the extensive damage seen in full thickness burns. Thus, recognizing the appearance of a full thickness burn is essential for proper assessment and treatment planning.