(Heterotopic) Calcification -
Abnormal calcium deposits.
|New Posts||Previous Posts|
Insoluble inorganic calcium salts are a normal constituent of bones and teeth.
Pathologic (Heterotopic) Calcification is the deposition of calcium salts in tissue other than osteoid and enamel.
The abnormal calcium deposits are present in injured and dead tissue.
The two main types are :
- Dystrophic Calcification:
- Metastatic Calcification:
In dystrophic calcification, serum calcium levels are normal and the calcium salts are deposited in dead or degenerate tissues.
This occurs in following sets of circumstances:
- Caseous calcification : Calcification is the key feature of old caseation. Example: Tuberculosis
- Fat necrosis : Traumatic fat necrosis seen in the breast.
Cystic degeneration may occur resulting in a cavity.
Calcification develops in the cyst wall. Fat necrosis in acute pancreatitis.
- Thrombosis : Example: Calcified left ventricular thrombus, Coronary Artery Calcification, Calcified thrombus of the inferior vena cava in children, calcified superior vena cava thrombosis.
- Infarction : Example: Gamna-Gandy bodies in the spleen are nodular lesions containing fibrous tissue, haemosiderin and calcium. These are secondary to localized areas of haemorrhagic infarction.
- Haematoma. Example: Subdural haematoma or myositis ossificans.
- Atherosclerotic plaques.
- Chronic inflammation - Granulation tissue. Example: Constrictive pericarditis.
- Monckeberg's sclerosis - Monckeberg's sclerosis is a special form of arteriosclerosis characterized by calcification and ossification of the media of medium size arteries mainly of lower extremities.
- Infection - Schistosomiasis - Calcification of the ureters, bladder and seminal vesicles may occur in genitourinary schistosomiasis.
Diagnosis of congenital toxoplasmosis , an infection involving the central nervous system, is suggested by the visualization of calcification in the infant brain.
- Degenerate colloid goitres
- Cysts of various types
- Calcinosis Cutis. Visit: Pathology of Calcinosis Cutis
- Degenerate tumour. Example: Uterine leiomyoma
In this condition the main defect is an elevated blood calcium level.
This may result from the removal of calcium from the bones.
Example: In hyperthyroidism or from excess calcium derived from the gut. In some cases high blood phosphate as in renal osteodystrophy.
This type of calcium deposition occurs in a variety of sites.
- The kidney - Deposition occurs round the tubules and damages them. Ultimately this may lead to renal failure.
These patients often show an inability to acidify their urine.
Stone formation in the renal pelvis and ureter is often associated with nephrocalcinosis.
- The lung - Calcium is deposited in the alveolar walls.
- The stomach. The calcium is deposited around fundic glands.
It has been suggested that since these glands secrete hydrochloric acid, the tissue are left relatively alkaline and this is said to favour calcium deposition.
- Blood vessels
Causes of Metastatic Calcification:
There are five common causes of metastatic calcification:
1. Hyperparathyroidism, either as a result of primary or secondary hyperplasia, or as a result of neoplasia (parathyroid adenoma), the commonest type of parathyroid hyperactivity.
2. Excessive absorption of calcium from the bowel, which may be due to hypervitaminosis D or vitamin D sensitive states such as idiopathic hypercalcemia of infancy or even through excessive milk drinking.
4. Destructive bone lesions
5. Renal tubular acidosis
3 to 5 are less common
Identification of Heterotopic Calcification:
On histological examination calcium salts appear as granules which stain a deep blue colour with haematoxylin.
They form encrustations on such structures as elastic fibres in the lung or in arteries.
Calcium salts can be stained with alizarin red S which stains them a magenta colour.
More commonly the von Kossa method is used, in which silver impregnation forms the basis of the stain.
What it shows is, in fact phosphate and carbonate, but since these are almost always associated with calcium when in its particulate and insoluble form, it constitutes quite an effective method fot the demonstration of calcium.
Other form of Pathologic Calcification:
Another form of pathologic calcification is the formation of stones containing calcium carbonate in sites such as the gallbladder, renal pelvis (discussed in metastatic calcification) , bladder, and pancreatic duct.
Stones in pancreatic duct Stones in urinary bladder
Stones in gallbladder
Under certain circumstances, the mineral salts precipitate from solution and crystallize around foci of organic material.
|New Posts||Previous Posts|
Copyright © 2017 pathopedia-india.com