Pathology dictionary

What is osteoid?

Osteoid is a chemical that the body uses to make bone. Osteoid is made by special cells called osteoblasts which are responsible for making new bone. When viewed under the microscope, new osteoid looks blue but later turns pink as minerals such as calcium are added to make it stronger.

It is normal to find osteoid inside of bone. Osteoid can also be found inside non-bone tissue and when this happens it may be described as heterotopic ossification. Heterotopic ossification commonly develops after an injury, but it is often a normal finding in older adults.
Both non-cancerous and cancerous tumour cells can also make osteoid.

Non-cancerous tumours that make osteoid include:

  • Osteoid osteoma
  • Osteoblastoma

Cancerous tumours that make osteoid include:

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