Patterns of tissue necrosis

Question 1

Caseous necrosis

Answer 1

is a pattern of necrosis seen with mycobacterial or certain fungal (eg, Histoplasma, Cryptococcus) infections.

Collections of epithelioid macrophages and giant cells surround white, friable, cheese-like material made up of cell fragments and proteinaceous debris (ie, caseating granulomas).

Question 2

Fat necrosis

Answer 2

occurs in areas with high numbers of adipocytes (eg, pancreas, breast, subcutaneous fat) and is frequently seen in pancreatitis.

Enzymes released from damaged cells break down triglycerides into free fatty acids, which combine with calcium to form soaps; anucleated adipocytes with calcium deposits are visible on microscopy.

Question 3

Fibrinoid necrosis

Answer 3

is a histologic pattern of injury seen in the walls of blood vessels affected by vasculitis or malignant hypertension.

It results from immune complexes and/or plasma proteins (eg, fibrin) leaking through the damaged intima and depositing within the vessel wall; the deposits appear histologically as a circumferential ring of pink, amorphous material surrounding the vascular lumen.

Question 4

Dystrophic calcification

Answer 4

occurs in areas of tissue injury or necrosis that escape removal by phagocytes. Phosphate ions in the necrotic tissue bind calcium to form salts, which can appear grossly as white granules and microscopically as amorphous, basophilic material on hematoxylin and eosin stain. However, the calcification develops slowly over the months and years following the initial injury.

Question 5

Coagulative necrosis

Answer 5

E. Irreversible ischemic injury outside CNS

M: Tissue architecture is preserved due to denaturation of lytic enzymes:

Cells are anucleate with eosinophilic cytoplasm

Leukocytes eventually infiltrate & digest necrotic tissue

Question 6

In most organs, irreversible ischemic injury typically results in coagulative necrosis. Because the digestive enzymes denature before they can significantly disrupt tissue integrity, the cellular architecture is maintained but nuclei are absent.

A major exception is tissue within the CNS, in which ischemia (eg, stroke) causes liquefactive necrosis with digestion of cellular constituents and liquefaction of necrotic tissue

Answer 6

In most organs, irreversible ischemic injury typically results in coagulative necrosis. Because the digestive enzymes denature before they can significantly disrupt tissue integrity, the cellular architecture is maintained but nuclei are absent. A major exception is tissue within the CNS, in which ischemia (eg, stroke) causes liquefactive necrosis with digestion of cellular constituents and liquefaction of necrotic tissue

Question 7

Lethal tissue ischemia causes __ __ in most tissues (eg, kidney, myocardium); cellular architecture is maintained but nuclei are absent.

The exception is ischemic cell death in the __, which causes liquefactive necrosis.

Answer 7

Lethal tissue ischemia causes coagulative necrosis in most tissues (eg, kidney, myocardium); cellular architecture is maintained but nuclei are absent.

The exception is ischemic cell death in the CNS, which causes liquefactive necrosis.