Necrosis

[Robbins 9th 43]

Explanation :
Coagulative necrosis is a form of necrosis in which the architecture of dead tissue is preserved for a span of at least some days .
The affected tissue has a firm texture. Presumably, the injury denatures not only structural proteins but also enzymes and so blocks the proteolysis of the dead cells; as a result, intensely eosinophilic cells with indistinct or reddish nuclei may persist for days or weeks.
Ultimately, the necrotic cells are broken down by the action of lysosomal enzymes derived from infiltrating leukocytes, which also remove the debris of the dead cells by phagocytosis. Ischemia caused by obstruction in a vessel may lead to coagulative necrosis of the supplied tissue in all organs except the brain (see next paragraph for explanation).
A localized area of coagulative necrosis is called an infarct.

Enzymatic fat necrosis occurs in pancreas

Liquefactive necrosis is seen in abscess

Explanation :
Avuscular necrosis seen in :
Head of femur
Talas
Scaphoid
Radiation therapy
Sickle cell crisis
Trauma 
Tumor

Explanation :
Coagulative necrosis :
Occurs in solid organ except brain
Example - Infract of heart ( MI),Kidney,Spleen,Gumma of tertiary syphilis. 

Explanation :
Features of irreversible cell injury -
Membrane injury
Intracellular release and activation of lysosomal enzyme 
Increase calcium influx
Decreased basophilia
Phagocytosis.

Explanation :
Site of traumatic fat necrosis -
Mostly breast
Then- salivary gland 
Pancreas
Neonates after delivery. 

Fibrinoid necrosis is seen in SLE

Explanation -
Necroptosis -is a hybrid that shares aspects of both necrosis and apoptosis. Morphologically, and to some extent biochemically, it resembles necrosis, as both are characterized by loss of ATP, swelling of the cell and organelles, generation of reactive oxygen species (ROS), release of lysosomal enzymes, and ultimately rupture of the plasma membrane.
Mechanistically, it is triggered by signal transduction pathways that culminate in cell death, a feature similar to apoptosis. Because of these overlapping features, necroptosis is sometimes called programmed necrosis to distinguish it from forms of necrosis driven passively by toxic or ischemic injury to the cell. 
Can occur both physiology and pathological condition.

[Robbins 9th 59]

Liquefactive necrosis occure in Pyogenic bacterial infection, brain hypoxia.