Which description corresponds to 4th-degree frostbite?

• A. Extends deeper into muscle, tendon and bone; mottled skin and nonblanching cyanosis with dry mummified eschar
• B. Partial thickness freezing with erythema and edema
• C. Formation of clear bullae, numbness followed by aching
• D. Freezing of skin and subdermal plexus with hemorrhagic bullae

Answer: (A)

Frostbite is graded by how deeply the tissue is frozen. The deepest form involves not just skin but structures beneath, extending into muscle, tendon, and bone. The description that fits this level shows skin that is mottled and nonblanching cyanotic, with tissue death producing a dry, mummified eschar. That dry eschar and deep tissue involvement are hallmarks of fourth-degree frostbite, indicating irreversible damage to the deepest tissues.

Other descriptions reflect shallower injuries: superficial frostbite affects only the skin with redness and pain; partial-thickness involvement presents with erythema, edema, and blistering limited to the dermis; hemorrhagic bullae and numbness point to deep dermal or subdermal injury but not necessarily bone or muscle involvement.