Calcium is a mineral found throughout the body. Cells need calcium to function normally. Pathologists use the term calcification 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 see calcium inside a tissue sample.
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 the microscope. It is not normal to see calcifications in other types of tissues.
There are many reasons for finding calcifications inside of 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:
Microcalcification is a word pathologists use to describe very small calcifications. Microcalcifications can be seen any where 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.
A psammoma body is a term pathologists use to describe a special type of calcification. A psammoma body is different from other types of calcifications because it is round and is made up of many layers. When examined under the microscope, a psammoma body looks like the inside of a sliced onion.