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Cellular Fatty Change (view source)
Revision as of 14:14, 24 December 2014
, 14:14, 24 December 2014→Gross Appearance of Fatty Change
==Introduction==
==Introduction==
* ''NB This term does not refer to the fat stores within the body!''
* ''NB This term does not refer to the fat stores within the body!''
** Fatty substances accumulate or increase within the cytoplams of specific cells.
** Fatty substances accumulate or increase within the cytoplasm of specific cells.
** In some instances, the fat stores may be involved in the transfer of fat to these specific cells.
** In some instances, the fat stores may be involved in the transfer of fat to these specific cells.
* Cellular fatty change is an important intracellular abnormality.
* Cellular fatty change is an important intracellular abnormality.
* [[Liver - Anatomy & Physiology|Liver]]
* [[Liver - Anatomy & Physiology|Liver]]
** This is the main organ involved in fatty change.
** This is the main organ involved in fatty change.
** May be greatly increased in size.
** May be greatly increased in size with rounded edges.
** Is tan to yellowish in colour.
** Is tan to yellowish in colour.
*** Is normally reddish brown.
*** Is normally reddish brown.
*** I.e. those muscles furthest away from the blood supply.
*** I.e. those muscles furthest away from the blood supply.
** Contractile ability is reduced, and blood is therefore not pumped efficiently.
** Contractile ability is reduced, and blood is therefore not pumped efficiently.
===Histological Appearance of Fatty Change===
===Histological Appearance of Fatty Change===
* The fat either appears as globules or is contained in varying sizes of vacuoles in the cytoplasm.
* Fat appears as clear colourless vacuoles of varying sizes in the cell cytoplasm.
** In the heart, fat appears as groups of tiny vacuoles dispersed along the myofibrils.
** In the heart, fat appears as groups of tiny vacuoles dispersed along the myofibrils.
** In the [[Liver - Anatomy & Physiology|liver]] and kidney, vacuoles tend to coalesce to form larger ones.
** In the [[Liver - Anatomy & Physiology|liver]] and kidney, vacuoles tend to coalesce to form larger ones.
*** One or more large globules may fill the cytoplasm.
*** One or more large vacuoles may fill the cytoplasm.
**** The nucleus is displaced to the periphery of the cell.
**** The nucleus is displaced to the periphery of the cell.
* The nucleus remains normal.
* The nucleus remains normal.
* In hepatocytes, it is necessary to stain for fat in order to ellucidate if a vacuole in the cytoplasm is fat-containing.
* In hepatocytes, it is necessary to stain for fat in order to ellucidate if a vacuole in the cytoplasm is fat-containing.
** Two further conditions may produce vacuoles in hepatocytes.
** Two further conditions may produce vacuoles in hepatocytes.
*** [[Degenerations and Infiltrations - Pathology#Vacuolar Degeneration|Vacuolar hydropic degeneration]]
*** [[Hydropic Degeneration#Vacuolar Degeneration|Vacuolar hydropic degeneration]]
*** Glycogen accumulation
*** Glycogen accumulation
** Stains commonly used include Sudan 111, Sudan 1V, and Oil Red O.
** Stains commonly used include Sudan III, Sudan IV, and Oil Red O.
*** Stain fat varying shades of orange to red.
*** Stain fat varying shades of orange to red.
** Sections must be prepared differently to the routine paraffin embedding (used e.g. in H&E staining).
** The strong solvents used in paraffin embedding dissolve the fat out of the cell.
*** Sections must therefore be prepared differently to the routine paraffin embedding (used e.g. in H&E staining).
*** When staining for fat, the tissue to be examined is frozen and sectioned in a cryostat before being stained.
*** When staining for fat, the tissue to be examined is frozen and sectioned in a cryostat before being stained.
**** These sections are more than twice as thick as those attained by sectioning paraffin blocks
**** These sections are more than twice as thick as those attained by sectioning paraffin blocks
***** There may be some overlap of cells on the section.
***** There may be some overlap of cells on the section.
**** Excessive destruction of erythrocytes (haemolysis).
**** Excessive destruction of erythrocytes (haemolysis).
** Circulatory disorders
** Circulatory disorders
*** [[Ischaemia and Infarction - Pathology#Ischaemia|Ischaemia]]
*** [[Ischaemia|Ischaemia]]
**** Reduced blood supply to a tissue
**** Reduced blood supply to a tissue
*** Chronic [[Venous Congestion and Hyperaemia - Pathology|venous congestion]]
*** Chronic [[Venous Congestion|venous congestion]]
**** Slowing of blood flow through the vasculature e.g. due to a failing heart.
**** Slowing of blood flow through the vasculature e.g. due to a failing heart.
* '''Extracellular accumulation of lipids'''
* '''Extracellular accumulation of lipids'''
** [[Necrosis - Pathology|Necrosis]] of cells containing lipid may release lipid into the extracellular space.
** [[Necrosis - Pathology|Necrosis]] of cells containing lipid may release lipid into the extracellular space.
*** [[Haemorrhage - Pathology|Haemorrhage]] or tissue damage may result in cholesterol being released from cells or pooled from lipoproteins in crystalline form (cholesterol clefts).
*** [[Haemorrhage|Haemorrhage]] or tissue damage may result in cholesterol being released from cells or pooled from lipoproteins in crystalline form (cholesterol clefts).
==Cardiac==
==Cardiac==
[[Category:Myocardial_Pathology]][[Category:General Pathology]]
Cellular fatty change is an important intracellular abnormality where fatty substances accumulate or increase within the cytoplasm of specific cells.
Principally this pathology affects the intracellular fat in hepatocytes, but the kidney and the heart can also be involved in [[Cellular Fatty Change|cellular fatty changes]]. These organs are susceptible as they are involved in the metabolism of fat, or are dependant upon lipids as an energy source. In some instances, the fat stores may be involved in the transfer of fat to these specific cells.
Fatty change can be readily recognised at post-mortem.
[[Category:Degenerations and Infiltrations]]
[[Category:Myocardial_Pathology]]
[[Category:Cardiovascular_System_-_Metabolic_Pathology]]
[[Category:Cardiovascular_System_-_Metabolic_Pathology]]
[[Category:Cardiology Section]]