What are the four main types of necrosis?

The four main types of necrosis are coagulative, liquefactive, caseous, and fat necrosis.

Coagulative necrosis is typically associated with ischemic events that cause cell death while preserving the basic tissue architecture. This type is commonly observed in heart attacks and occurs due to the denaturation of proteins and enzymes.

Liquefactive necrosis leads to the transformation of tissue into a liquid viscous mass, primarily seen in brain injuries or infections where enzymatic breakdown occurs rapidly. This type is characterized by the accumulation of pus and is common in bacterial infections.

Caseous necrosis is often linked to tuberculosis infections, where the affected tissue appears cheese-like or caseous due to the presence of necrotic tissue surrounded by inflammation. This specific appearance is due to the immune response to mycobacterial infection.

Fat necrosis occurs when there is damage to adipose tissue, commonly associated with pancreatitis or trauma. It involves the formation of fatty acids that bind with calcium, leading to necrosis in the fatty tissues.

Collectively, these four types of necrosis cover the principal mechanisms of cell death and tissue reaction to injury, making answer A the correct choice.