Necrosis is the death of body tissue. It occurs when too little blood flows to the tissue. This can be from injury, radiation, or chemicals. Necrosis cannot be reversed.
When large areas of tissue die due to a lack of blood supply, the condition is called gangrene.
Wallig MA, Janovitz EB. Morphologic manifestations of toxic cell injury. In: Haschek WM, Rousseaux CG, Wallig MA. Haschek and Rousseaux's Handbook of Toxicologic Pathology. 3rd ed. Waltham, MA: Academic Press, Elsevier; 2013:chap 4.