Eschar

Eschar is a dry, dark crust of dead tissue that forms over a wound or lesion as necrotic material accumulates. It differs from a typical scab in that eschar consists largely of devitalized tissue rather than dried blood and inflammatory exudate. The term is used in dermatology and wound care to describe necrotic tissue accompanying various injuries and infections.

Causes include severe burns (thermal or chemical), deep frostbite, and pressure ulcers; infections can also lead to eschar formation. A well-known infectious example is cutaneous anthrax, which classically presents with a painless black eschar surrounded by edema. Eschars can also appear in other noninfectious injuries and chronic wounds.

Pathophysiology and appearance: Necrosis of skin and underlying tissue produces a firm, adherent crust that is often black or brown. The eschar can obscure signs of infection and impede re-epithelialization. In burns with circumferential deep tissue injury, the eschar may restrict perfusion and necessitate surgical intervention.

Management: Treatment focuses on removing nonviable tissue (debridement) as appropriate and addressing the underlying cause. Wound care aims to maintain a moist, clean environment to promote healing and reduce infection risk. If systemic infection develops, prompt medical evaluation is required. In severe circumferential burns, an escharotomy may be indicated to relieve pressure.

Prognosis and prevention: Timely debridement and appropriate wound care facilitate healing and reduce complications. Prevention emphasizes burn safety, protective measures against frostbite, and rapid management of infections to limit necrosis.