Necrosis is irreversible injury and death of cells and living tissue. There are several patterns of necrosis that can occur in tissues including coagulative, liquefactive, and caseous necrosis. Coagulative necrosis involves the maintenance of cell outlines but loss of cellular details. The dead tissues remain in the body for a long period. Liquefactive necrosis results from the rapid dissolution of dead cells, often leading to abscess formation. Caseous necrosis converts dead tissue into a granular mass resembling cottage cheese, associated with tuberculosis lesions.