Calcification is the accumulation of calcium salts in a body tissue. It normally occurs in the formation of bone, but calcium can be deposited abnormally in soft tissue, causing it to harden. Calcifications may be classified on whether there is mineral balance or not, and the location of the calcification. Calcification may also refer to the processes of normal mineral deposition in biological systems, such as the formation of stromatolites or mollusc shells (see Mineralization (biology) or Biomineralization).
Calcification of soft tissue (arteries, cartilage, heart valves, etc.) can be caused by vitamin K2 deficiency or by poor calcium absorption due to a high calcium/vitamin D ratio. This can occur with or without a mineral imbalance.
Intake of excessive vitamin D can cause vitamin D poisoning and excessive intake of calcium from the intestine, when accompanied by a deficiency of vitamin K (perhaps induced by an anticoagulant) can result in calcification of arteries and other soft tissue. Such metastatic soft tissue calcification is mainly in tissues containing "calcium catchers" such as elastic fibres or sour mucopolysaccharides. These tissues especially include the lungs (pumice lung) and the aorta.
Calcification can manifest itself in many ways in the body. Several conditions can be caused by poor calcium absorption:
Patterns of calcifications may indicate pathological processes. Laminated appearance suggests granulomatous disease while popcorn calcification indicates hamartoma. Malignant lesions may have stippled or eccentric calcification.
In a number of breast pathologies, calcium is often deposited at sites of cell death or in association secretions or hyalinized stroma, resulting in pathologic calcification. For example, small, irregular, linear calcifications may be seen, via mammography, in a ductal carcinoma-in-situ to produce visible radio-opacities.