Giant cell tumors are so named because when viewed under a microscope, giant cells with multiple nuclei are observed. They affect the bones, particularly the long bones, such as the distal femur (end of the thigh bone near the knee), proximal tibia (top of the lower leg bone), and distal radius (one of two bones in the forearm).
Giant cell tumors of the sacrum are relatively rare. They are benign in the sense that they don’t usually spread to other parts of the body. And they don’t cause death directly. But they can be very invasive, spreading locally into more and more of the bone where they originated. The tumor can metastasize to the lungs. This is rare, but occurs in one to five per cent of patients.
A giant cell tumor in the sacral area can be very invasive locally. If it is removed, it often comes back as patients have a high rate of recurrence. In some cases, the tumor may turn into a malignant tumor. This type of occurence is relatively uncommon but it can happen. The prognosis is poor in these cases.
Most tumors of the sacrum (including giant cell tumors) are slow growing. There aren’t very many signs or symptoms until it gets big enough to press on nearby nerves, blood vessels, or soft tissues. That also means by the time the patient starts having some problems and gets a diagnosis, the problem can be very far advanced.
Treatment can involve major surgery with removal of the affected bone. Complications such as bowel and bladder loss or sexual dysfunction can develop (either as a result of the tumor or in the process of removing the tumor). The tumor can come back again, so patients are followed for at least two years.