November 28, 2023

In pathology, the term calcification is used to describe the build-up of calcium inside of tissue. When examined under a microscope areas of calcification look much darker than the surrounding normal tissue and these areas can be seen on routine H&E stained slides. Pathologists can also perform a special stain called a von Kossa stain to highlight calcium deposits inside a tissue sample.

This picture shows multiple areas of calcification in the breast.

Where is calcium normally found in the body?

Most of the calcium in our body is found in our bones where it is used to make the bones strong. Small amounts of calcium are also found inside cells throughout our body and in our blood. It is normal to see calcification when looking at bones under a microscope. It is not normal to see calcifications in other types of tissues.

What causes calcification?

There are many reasons for finding calcifications inside a tissue sample. The cause depends on the type of tissue involved and your medical history. Other changes seen around the area of calcification can also help determine the cause. Tissues that die may calcify especially in young people.  Older people may also get calcium in some of their tissues as they get older.

The most common causes for calcifications are:

  • Injury or infection – Any tissue that is damaged by an injury or infection can develop calcifications. Calcifications can also be caused by a previous medical procedure such as a biopsy. Sometimes the calcifications are so large that they can be felt when the tissue is touched. The calcifications are caused by calcium released from the damaged cells.
  • Tumours – Some tumours can cause calcifications as the cells in the tumour die and release their calcium into the surrounding tissue. Calcifications can be seen in both non-cancerous and cancerous tumours. Calcifications are very commonly seen in tumours of the breast. Pathologists sometimes describe calcifications seen with a tumour as dystrophic calcification.
  • Chronic inflammationChronic inflammation is a term pathologists use to describe a type of immune response that lasts for a long time (usually weeks, months, or even years). Over time, chronic inflammation can damage the surrounding tissue and cause calcifications to develop. Calcifications caused by chronic inflammation are commonly seen in blood vessels, especially in people older than 50 years of age.
  • Increased calcium in the blood –  Increased calcium in the blood is called hypercalcemia. If hypercalcemia is severe (very high) or continues for a long period of time, some of the calcium can leave the blood and enter the surrounding tissue. In this situation, calcifications can be seen in the walls of the blood vessels or the tissue surrounding the blood vessels.

What is microcalcification?

Microcalcification is a word pathologists use to describe very small calcifications. Microcalcifications can be seen anywhere in the body although this description is most commonly used to describe small calcifications in the breast. Radiologists also use the word microcalcifications to describe small calcifications seen on radiological images.

About this article

Doctors wrote this article to assist you in reading and comprehending your pathology report. Feel free to reach out to us with any questions about this article or your pathology report. To get a comprehensive introduction to your pathology report, read this article.

Other helpful resources

Atlas of pathology
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