Pathopedia-India.com: Pathologic Calcification

The deposition of mineral salts of calcium is a normal process in the formation of bone from cartilage. Calcium entry into dead or dying cells is usual, owing to the inability of such cells to maintain a steep calcium gradient. This cellular calcification is not ordinarily visible except as inclusions within mitochondria.

Pathologic calcification is the abnormal deposition of calcium salts in soft tissue.

- Dystrophic Calcification:

Dystrophic calcification refers to the macroscopic deposition of calcium salts in injured tissues. This type of calcification does not simply reflect an accumulation of calcium derived from the bodies of dead cells, but rather represents an extracellular deposition of calcium from the circulation or interstitial fluid.

Dystrophic calcification requires the persistence of necrotic tissue. It is often visible to the naked eye, and ranges from gritty, sand-like grains to firm, rock-hard material.

In many locations, such as in case of tuberculous caseous necrosis in the lung or lymph nodes, calcification has no functional consequences. Visit: Tuberculosis

Dystrophic calcification may also occur in crucial locations, such as in the mitral or aortic valves after rheumatic fever. In such instances, calcification leads to impeded blood flow because it produces inflexible valve leaflets and narrowed valve orifices (mitral and aortic stenosis). Dystrophic calcification in atherosclerotic coronary arteries contributes to narrowing of those vessels. Cardiac Path Online

Dystrophic calcification also plays a role in diagnostic radiography. Mammography is based principally on the detection of calcification in breast cancers.

Diagnosis of congenital toxoplasmosis , an infection involving the central nervous system, is suggested by the visualization of calcification in the infant brain.

[ SUMMARY: Dystrophic calcification occurs in nonviable or dying tissues in the presence of normal calcium serum level. This is seen in arteries in atherosclerosis, in damaged heart valves and in areas of necrosis (coagulative, caseous and liquifactive). Calcium can be intracellular, extracellular or in both locations. ]

- Metastatic Calcification:

Where as dystrophic calcification has its origin in cell injury, metastatic calcification reflects deranged calcium metabolism, a change associated with an increased serum calcium concentration (hypercalcemia). In general, almost any disorder that increases the serum calcium level can lead to calcification in such inappropriate locations as the alveolar septa of the lung, renal tubules, and blood vessels. Calcification is seen in various disorders, including chronic renal failure, vitamin D intoxication, hyperparathyroidism. In contrast to dystrophic calcification, the metastatic variety does not require pre-existing cell injury.

Causes of Metastatic Calcification:

1. Increased secretion of parathyroid hormone.

2. Destruction of bone tissue as occurs with primary tumours of bone marrow (e.g. multiple myeloma) or by diffuse skeletal metastasis (e.g. breast cancer)

3. Vitamin D - related causes including vitamin D intoxication and systemic sarcoidosis.

4. Renal failure (causing secondary hyperparathyroidism).

[ SUMMARY: Metastatic calcification is the deposition of calcium salts in vital tissues and is always associated with hypercalcemia. Calcium deposits are seen as amorphous basophilic densities that may occur widely throughout the body, affecting the interstitial tissues of blood vessels, kidneys, lungs and stomach. ]

- 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, bladder, and pancreatic duct. Under certain circumstances, the mineral salts precipitate from solution and crystallize around foci of organic material.