What is a typical appearance of skin during fourth degree frostbite?

In fourth degree frostbite, the appearance of the skin is significantly altered due to extended exposure to extreme cold, leading to more severe damage than in less severe degrees of frostbite. The skin typically presents a deeply red and mottled appearance as the tissue undergoes necrosis and becomes irreversibly injured.

This mottled effect occurs due to the destruction of blood vessels and the eventual ischemia of deeper structures, which can lead to gangrene. Skin at this stage is often nonviable, indicating that the damage extends to muscles, tendons, and possibly bone beneath the skin layer.

While other degrees of frostbite have different characteristics—such as pale white skin in early stages (indicating vasoconstriction), bright red and swollen in first degree (as irritation and inflammation occur), or clear blistering in second degree—the distinctive mottled deep red appearance in fourth degree frostbite reflects the severity and extent of tissue damage, signifying that immediate medical intervention is necessary.