* Osteoid is a protein mixture secreted by osteoblasts that forms the organic matrix of bone. Bone is formed when osteoid mineralizes. osteoid is the unmineralized, organic portion of the bone matrix that forms prior to the maturation of bone tissue.
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▪ItistheDeposition/AccumulationofCalciumphosphateandother
calcificsaltsintissueotherthanosteoid*orenamel.
▪Thedepositionmaybeintracellular,extracellularoratboththe
locations.
▪Therearetwotypesofpathologiccalcification:
1. Dystrophic Calcification2. Metastatic Calcification
* Osteoidis a protein mixture secreted by osteoblasts that forms the organic matrix of bone. Bone is
formed whenosteoidmineralizes. osteoidis the unmineralized, organic portion of the bone matrix that
forms prior to the maturation of bone tissue.
Pathologic Calcification
1. Dystrophic calcification
▪Encountered in areas of necrosis.
▪It is the deposition of calcium salts in dead or degenerated tissues
▪Occurs at normal Calcium metabolism and normal serum calcium level.
2. Metastatic Calcification
▪Occurs in normal tissues.
▪Associated with deranged calcium metabolism and hypercalcaemia.
Pathologic Calcification: Types
▪It is encountered in areas of necrosis, whether they are of
coagulative, caseous, or liquefactive type, and in foci (place)
of enzymatic necrosis of fat.
▪Calcification is almost always present in the atheromas*of
advanced atherosclerosis**.
▪It also commonly develops in aging or damaged heart
valves, further hampering their function.
❖*Atheroma, or atheromatous plaque ("plaque"), is an abnormal accumulation
of material in the inner layer of the wall of an artery
❖**Atherosclerosisis a disease in which plaque builds up inside arteries.
Pathologic Calcification: Types
1. Dystrophic Calcification
▪The calcium salts appear macroscopicallyas
fine, white granulesor clumps, often felt as
gritty deposits.
▪Dystrophic calcification may simply be a
telltale sign of previous cell injury, it is often
a cause of organ dysfunction.
Dystrophic calcification of the aortic valve
Pathologic Calcification: Types
1. Dystrophic Calcification
May occur in normal tissues whenever there is hypercalcaemiawould include one of the
following two conditions:
1.Excessive mobilization of calcium from the bone.
2.Excessive absorption of calcium from the gut.
These causes are more common and include the following :
1.Hyperparathyroidism
2.Bony destructive lesions
3.Prolonged immobilization of a patient results in disuse atrophy of the bones and
hypercalcaemia
Pathologic Calcification: Types
2. Metastatic calcification
Less often, excess calcium may be absorbed from the gut causing hypercalcaemia and
metastatic calcification. These causes are as under:
1.Hypervitaminosis-Dresults in increased calcium absorption.
2.Milk-alkali syndrome caused by excessive oral intake of calcium in the form of milk
and administration of calcium carbonate in the treatment of peptic ulcer.
3.Hypercalcaemia of infancy is another condition in which metastatic calcification
may occur.
Sites of Metastatic Calcification
▪Metastatic calcification can occur in any normal tissue of the body but affects the
following organs more commonly
-Kidney -Lungs, especially in the alveolar walls
-Stomach -Blood Vessels
-Cornea -Synovium
Pathologic Calcification: Types
2. Metastatic calcification
Difference Between Dystrophic & Metastatic Calcification
Pathologic Calcification
Feature Dystrophic Calcification Metastatic Calcification
Definition Deposition of calcium salts in dead and degenerated
tissues.
Deposits of calcium salts in normal tissues.
Calcium MetabolismNormal Deranged
Serum calcium levelNormal Hypercalcaemia
Reversibility Generally irreversible Reversible upon correction of metabolic
disorder.
Causes Necrosis (caseous, liquefactive, fat), old scars,
atheromas,
Hyperparathyroidism, prolonged
immobilization, hypervitaminosis-D, milk-
alkali syndrome, hypercalcaemia of infancy
Pathogenesis Increased binding of phosphates with increased
necrotic and degenerative tissue, which in turn binds
to calcium forming calcium phosphates.
Precipitation of calcium phosphate due to
hypercalceamiaat certain sites e.g. in
lungs, stomach, cornea,
Dystrophic & Metastatic Calcification
Pathologic Calcification
Practice Questions
1.What do you mean by pathologic calcification? Discuss.
2.Classify pathologic calcification with suitable examples.
3.Discuss the pathogenesis of dystrophic calcification.
4.What are the major sites of metastatic calcification?
5.What is the Difference Between Dystrophic & Metastatic Calcification.
6.Define following terms:
▪Osteoid
▪Osteoblasts
▪Hypercalcaemia
▪Coagulative, caseous and liquefactive Necrosis
▪Atheromas
▪Atherosclerosis
▪Hypervitaminosis-D