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Patomorfologia

Wykład 02

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Necrosis

• Morphologic changes that follow cell

death (irreversible injury) in living tissue

• Changes are due to degradative action

of enzymes and denaturation of

intracellular proteins

• Proteins ca be liberated from the dead &

detected in the blood for diagnosis

– CK-MB mycardial necrosis, AST/ALT -

hepatitis

Microscopic Changes

Necrosis

Light Microscopy & EM

• Increased cytoplasmic cosinophilia

– due to loss of RNA & ine binding of eosin

to coagulated proteins

• Nuclear pyknosis
• Karyorrhexis
• Karyolysis

Misroscopic Changes

Necrosis

• Disruption of plasma and membranes

• Rupture of lysosomes

• Dense bodies mitochondria (calcium)

– assoc / markedly swollen mitochondria

• Intracytoplasmic myelin figures

Necrosis -

Pyknosis

Light Microscopy

Patterns (Types) of Necrosis

• Coagulative

• Liquefactive

• Gangrenous

• Caseous

• Fat necrosis

Coagulative Necrosis

• Preservation of cellular outlines,

mocroscopically and general tissue
architecture grossly

• Mechanism

– intracellular acidosis and Ca influx denature

(preserve) structural proteins and enzymes
preventing proteolysis

• Cause

– ischemia – most common

• causes coagulative necrosis in all tissues except brain

(liquefactive necrosis)

• usually due to atherosclerosis

Coagulative Necrosis

• Ischemia: reduction in blood supply

due to obstruction of circulation

• Infarct: localized area of necrosis

(coagulative except in the brain)
resulting from ischemia

Coagulative Necrosis Kidney

Normal Kidney

Coagulative Kidney

Coagulative Necrosis Renal

infarct

non preservation of tissue architecture

Coagulative Necrosis -Heart

Normal Myocardium

Coagulative Myocarduim

Liquefactive Necrosis

• Complete loss of cell and tissue structure

– Cells / tissue usually replaced by neutrophils

•grossly

– pus
– abscesses; localized (well defined) area of

liqueactive necrosis

– Except ischemic brain; cystic cavity filled

with necrotic cell debris

Liquefactive Necrosis

• Mechanism

– proteolytic enzymes produced by

neutrophils (primarily), monocytes,
macrophages

– ischemic brain; non inflammatory cell

enzymes & lack of structural support

• Cause
• bacterial infections usually

– rarely fungi

Liquefactive Necrosis

Pulmonary Abscess

Liquefactive Necrosis - Lung

Normal Lung

Liquefactive Necrosis

Gangrenous Necrosis (Dry

Gangrene)

• Clinical term
• Coagulative necrosis of a limb / listal

extremity

– usually due of ischemia

• Wet gangrene

– liquefactive necrosis, due to bacterial

infection, superimposed or dry gangrene

Caseous Necrosis

• Type of coagulative necrosis
• Usually associated with M. tuberculosis

– less commonly with some fungal

infections such as histoplasmosis

• WHEN YOU SEE CASEOUS NECROSIS

THINK TUBERCULOSISUNTIL PROVEN
OTHERWISE

Liquefactive Necrosis - Lung

• Gross

– white „cheese-like” apperance

• Microscopie

– central area; amorphous granular

eosinophilic debris with complete

oblitaretion of tissue architecture

– surrounded by granulomatous

inflammation

• macrophages & Langhans type giant cells

• Type IV hypersensivity

Caseous Necrosis

Tuberculosis Lung

Fat Necrosis

• Focal areas of fat destruction with chalky

white deposits

– pancreas & peritoneal cavity

• Associated with acute pancreatitis
• Gross

– chalky white deposits; pancreas & peritoneal

cavity

• Microscopie

– adipocytes: cytoplasm amorphous eosinophile

material & basophilic material (ca deposits),

loss nuclei

Fat Necrosis

• Mechanism

– acute pancreatitis
– leakageof pancreatic lipase
– split triglycerides within adipocytes
– relase of free fatty acid
– free fatty acids + Ca
– saponification
– +/- hypocalcemia

Clinical Acute Pancreatis

• Epigastric pain that radiates to the back

• Elevated levels of amylase and lipase

• Association with alcoholism

Fat Necrosis – Pancreas

Adipose Tissue

Fibrinoid Necrosis

• Accumulation of eosinophilie material

within vessel walls

• Indication of severe damage to

wessel wall

• Occurs in malignant hypertension

and immune-mediated vasculitis &
other conditions

Apoptosis

„Apoptosis refers to a genetically
determined, internal, self-struct
mechanism of cell death, which is
activated under a variety of
conditions.”

Examples of Apoptosis

• Programmed destructions of cells during

embryogenesis

– organogenesis
– developmental involution

• Hormone dependent involution / atrophy in

adults

– endometrial breakdown menstruation, ovarian

follicle atresia menopause, regression lactating
breast, prostate atrophy castration

• Cell death in tumor regression

Examples of Apoptosis

• Death of autoreactive T-cells in

developing thymus

• Cell death by cytotoxic T-cells

– organ rejection, graft vs. host disease

• Certain viral & immune mediated

discases

– viral hepatitis – Councilman bodies
– lichem planus – Civatte bodies

Examples of Apoptosis

• Injurious stimuli; heat, radiation,

cytotoxic drugs

– apoptosis or necrosis depending on dose

• Loss of Mullerian structures in males

and Wolffian structures in females

• Cauce of bowel atresia

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