You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Necrosis of the entire skin thickness and variable thickness of underlying subcutaneous tissue is: and explain in detail?
1st degree frostbite is hyperaemia and edema of skin.
2nd degree frostbite is hyperaemia, vesicle formation and partial thickeness necrosis of skin.
 3rd degree frostbite is necrosis of entire skin thickeness and variable thickeness of underlying subcutaneous tissue.
4th degree frostbite is necrosis of entire thickeness of skin and all underlying structures leading to gangrene of the affected part.