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Mineralisation - Pathology (view source)
Revision as of 12:17, 15 February 2011
, 12:17, 15 February 2011Created page with "===Calcification=== * Calcification is the deposition of calcium in tissues other than bone and teeth. * Where sufficient amounts are..."
===Calcification===
* Calcification is the deposition of calcium in tissues other than bone and [[:Category:Teeth - Anatomy & Physiology|teeth]].
* Where sufficient amounts are deposited to be seen grossly, it imparts a whitish colour to the area.
* There are two types of calcification:
*# Dystrophic
*# Metastatic (Hypercalcaemia)
====Dystrophic====
* Occurs in damaged tissue.
** Dead tissue is alkaline - favours the deposition of calcium.
* Deposition is usually irreversible.
* NOT related to elevated levels of calcium in the blood.
* Commonly seen in:
** [[Necrosis - Pathology#Caseation Necrosis|Caseous necrosis]] in tuberculous [[Granulomatous Inflammation|granulomas]].
** Dead migrating [[Parasites|parasites]] in various tissues
** In part of Vit.E/selenium deficiency in livestock
*** Calcium is deposited in the necrotic tissue.
=====Gross Appearance=====
* Calcium salts have dull grey white chalky and granular appearance in tissue.
* Granules are hard.
** Feel gritty if cut or palpated.
=====Histological Appearance=====
* Stains as irregular blue-purple clumps (sometimes shattered) with H&E.
** Can be confused with bacteria.
* Von Kossa is a special stain that colours calcium black.
====Metastatic (Hypercalcaemia)====
* Metastatic calcification is calcification of normal tissue without previous damage.
* Is a result of hypercalcaemia.
* Calcium salts are laid down on basement membranes and elastic fibres, for example
** Blood vessel walls
** Pleura
** Mucous membranes of the lungs, kidneys, and [[Monogastric Stomach - Anatomy & Physiology|stomach]].
** Endocardium
** Tendons and ligaments of joints.
* '''Causes of hypercalcaemia'''
*# '''Primary Hyperparathyroidism'''
*#* A rare condition
*#* An adenoma of the parathyroid gland produces parathyroid hormone.
*#** Stimulates osteoclasts to resorb calcium from bone, producing hypercalcaemia.
*# '''Secondary Hyperparathyroidism'''
*#* '''Renal hyperthyroidism'''
*#** Occurs in chronic kidney failure.
*#** Kidneys retain phosphate.
*#*** Disturbs the calcium:phosphate ratio.
*#**** Stimulates the parathyroid gland to resorb calcium from bone.
*#** Calcium resorption from bone is compounded by lack of activated Vit. D.
*#*** This is due to the kidney damage.
*#* '''Nutritional hyperthyroidism'''
*#** The parathyroid stimulation here is due to excessive phosphates in the diet
*#*** E.g. a grain diet.
*#*** Upsets the calcium:phosphate ratio.
*#* '''Hypervitaminosis D'''
*#** Due to
*#*** Therapy
*#*** Ingestion of some plants which produce substances mimicking Vit. D .
*#** Results in increased calcium absorption from the gut, and hence hypercalcaemia.
*#* '''Tumours which produce hormone like activity'''
*#** E. g.
*#*** Some lymphosarcomas
*#*** Anal gland apocrine malignant tumour
*#*** Some carcinomas
====Other Conditions in Which Calcium is Deposited====
=====Calcinosis circumscripta=====
* A condition of dogs
** Particularly affects young German Shepherd Dogs.
* Nodules of a pasty calcium material are laid down in the dermis.
** Especially laid down near bony prominences.
* Aetiology is unknown,
** May be related to damage of sweat glands.
*** These are often in the vicinity of the deposits.
=====Calcinosis cutis=====
* In [[Adrenal Glands - Pathology#Adrenal Hyperfunction|Cushing’s Disease]] (hyperadrenocortism).
* Calcium is diffusely deposited on the collagen and elastin of the dermis .
===Ossification===
* A metaplastic change in soft tissues.
===Extracellular crystals ===
====Ethylene Glycol Poisoning====
* Accidental ethylene glycol (antifreeze) poisoning is not uncommon in small animals.
* Ethylene glycol is metabolised in the [[Liver - Anatomy & Physiology|liver]] to oxalate.
** Oxalate crystals precipitates in the renal tubules.
*** Can cause severe traumatic damage.
====Gout====
* Gout occurs with excessive retention of uric acid/urates and their deposition in tissue.
* Fairly common in man.
** The crystals are deposited in joint tissue, particularly those of the toe.
*** Sometimes occurs in the tarsal joints of birds.
* In birds, other tissues are more commonly affected.
** The serous membranes of the body cavities.
*** Look like they have been dipped in flour.
** The substance of the kidney
*** The star-shaped crystals may block the tubular lumen.
**** Their sharp edges may also damage the tubular epithelium and underlying basement membrane.
***** Provokes a host cellular response.
* The exact pathogenesis in birds is unknown.
** Birds excrete semisolid urates through the kidneys.
*** This may predispose them to blockages.
** Other suggested predispositions include
*** Vitamin A deficiency
*** Prior kidney damage due to an inflammatory process
*** Abnormal protein metabolism
* Tortoises are also susceptible to gout.
[[Category:General Pathology]]
* Calcification is the deposition of calcium in tissues other than bone and [[:Category:Teeth - Anatomy & Physiology|teeth]].
* Where sufficient amounts are deposited to be seen grossly, it imparts a whitish colour to the area.
* There are two types of calcification:
*# Dystrophic
*# Metastatic (Hypercalcaemia)
====Dystrophic====
* Occurs in damaged tissue.
** Dead tissue is alkaline - favours the deposition of calcium.
* Deposition is usually irreversible.
* NOT related to elevated levels of calcium in the blood.
* Commonly seen in:
** [[Necrosis - Pathology#Caseation Necrosis|Caseous necrosis]] in tuberculous [[Granulomatous Inflammation|granulomas]].
** Dead migrating [[Parasites|parasites]] in various tissues
** In part of Vit.E/selenium deficiency in livestock
*** Calcium is deposited in the necrotic tissue.
=====Gross Appearance=====
* Calcium salts have dull grey white chalky and granular appearance in tissue.
* Granules are hard.
** Feel gritty if cut or palpated.
=====Histological Appearance=====
* Stains as irregular blue-purple clumps (sometimes shattered) with H&E.
** Can be confused with bacteria.
* Von Kossa is a special stain that colours calcium black.
====Metastatic (Hypercalcaemia)====
* Metastatic calcification is calcification of normal tissue without previous damage.
* Is a result of hypercalcaemia.
* Calcium salts are laid down on basement membranes and elastic fibres, for example
** Blood vessel walls
** Pleura
** Mucous membranes of the lungs, kidneys, and [[Monogastric Stomach - Anatomy & Physiology|stomach]].
** Endocardium
** Tendons and ligaments of joints.
* '''Causes of hypercalcaemia'''
*# '''Primary Hyperparathyroidism'''
*#* A rare condition
*#* An adenoma of the parathyroid gland produces parathyroid hormone.
*#** Stimulates osteoclasts to resorb calcium from bone, producing hypercalcaemia.
*# '''Secondary Hyperparathyroidism'''
*#* '''Renal hyperthyroidism'''
*#** Occurs in chronic kidney failure.
*#** Kidneys retain phosphate.
*#*** Disturbs the calcium:phosphate ratio.
*#**** Stimulates the parathyroid gland to resorb calcium from bone.
*#** Calcium resorption from bone is compounded by lack of activated Vit. D.
*#*** This is due to the kidney damage.
*#* '''Nutritional hyperthyroidism'''
*#** The parathyroid stimulation here is due to excessive phosphates in the diet
*#*** E.g. a grain diet.
*#*** Upsets the calcium:phosphate ratio.
*#* '''Hypervitaminosis D'''
*#** Due to
*#*** Therapy
*#*** Ingestion of some plants which produce substances mimicking Vit. D .
*#** Results in increased calcium absorption from the gut, and hence hypercalcaemia.
*#* '''Tumours which produce hormone like activity'''
*#** E. g.
*#*** Some lymphosarcomas
*#*** Anal gland apocrine malignant tumour
*#*** Some carcinomas
====Other Conditions in Which Calcium is Deposited====
=====Calcinosis circumscripta=====
* A condition of dogs
** Particularly affects young German Shepherd Dogs.
* Nodules of a pasty calcium material are laid down in the dermis.
** Especially laid down near bony prominences.
* Aetiology is unknown,
** May be related to damage of sweat glands.
*** These are often in the vicinity of the deposits.
=====Calcinosis cutis=====
* In [[Adrenal Glands - Pathology#Adrenal Hyperfunction|Cushing’s Disease]] (hyperadrenocortism).
* Calcium is diffusely deposited on the collagen and elastin of the dermis .
===Ossification===
* A metaplastic change in soft tissues.
===Extracellular crystals ===
====Ethylene Glycol Poisoning====
* Accidental ethylene glycol (antifreeze) poisoning is not uncommon in small animals.
* Ethylene glycol is metabolised in the [[Liver - Anatomy & Physiology|liver]] to oxalate.
** Oxalate crystals precipitates in the renal tubules.
*** Can cause severe traumatic damage.
====Gout====
* Gout occurs with excessive retention of uric acid/urates and their deposition in tissue.
* Fairly common in man.
** The crystals are deposited in joint tissue, particularly those of the toe.
*** Sometimes occurs in the tarsal joints of birds.
* In birds, other tissues are more commonly affected.
** The serous membranes of the body cavities.
*** Look like they have been dipped in flour.
** The substance of the kidney
*** The star-shaped crystals may block the tubular lumen.
**** Their sharp edges may also damage the tubular epithelium and underlying basement membrane.
***** Provokes a host cellular response.
* The exact pathogenesis in birds is unknown.
** Birds excrete semisolid urates through the kidneys.
*** This may predispose them to blockages.
** Other suggested predispositions include
*** Vitamin A deficiency
*** Prior kidney damage due to an inflammatory process
*** Abnormal protein metabolism
* Tortoises are also susceptible to gout.
[[Category:General Pathology]]