Giant cell tumour of bone

What is a giant cell tumour?

Giant cell tumour of bone is a common type of bone tumour. It can start in almost any bone in the body. Although most giant cell tumours of bone are non-cancerous, they are aggressive at their site and can lead to a fracture or break of the bone. Some giant cell tumours of bone may grow beyond the bone and involve the surrounding tissues such as the muscle. Very rarely, a giant cell tumour of bone may be cancerous. Giant cell tumour of bone usually involves the ends of a bone. This type of tumour typically affects young adults.


Bones are a special type of tissue that provide our body with support and protection. In total there are 206 bones in our body. Some bones (like the bones in our fingers) are very small while other bones (like the bone in our upper leg) are very big.

Normal bones develop when special cells called osteoblasts produce a substance called osteoid which is initially soft but becomes hard over time as minerals (such as calcium) are added to it. Osteoid that is still soft is called ‘immature’ bone while mineralized hard osteoid is called ‘mature’ bone.

How do pathologists make this diagnosis?

Giant cell tumours of bone are typically diagnosed after a small sample of tissue is removed in a procedure called a biopsy. When examined under the microscope, the tumour is made up of two kinds of cells:

  1. Mononuclear cells – These are small round cells with a single nucleus.
  2. Osteoclast-like giant cells – These are very large cells that have more than one nucleus.

Your pathologist will look for both of these types of cells when examining your tissue sample under the microscope.


After the pathologist makes a diagnosis of giant cell of tumour of bone, the patient is often treated with surgery but may receive a medication called Denosumab prior to the surgery. The tumour is then removed completely as a resection specimen and sent to pathology for examination and to confirm the diagnosis.

by Bibianna Purgina, MD FRCPC, updated December 24, 2020
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