Giant Cell Tumor (Osteoclastoma)

Giant cell tumor (RZT) (synonyms: osteoclastoma; ICD-10-GM D48.0: neoplasm of uncertain or unknown behavior in other and unspecified locations: Bone and articular cartilage) refers to a benign neoplasm (neoplasm) of bone arising from the bone marrow. It is a rare tumor that used to be called osteoclastoma because of its osteoclastically active giant cells.

Giant cell tumor is a primary tumor. Typical for primary tumors is their respective course and that they can be assigned to a certain age range (see “Frequency peak”) as well as a characteristic localization (see “Symptoms – complaints” below). They occur more frequently at the sites of the most intensive longitudinal growth (metaepiphyseal/articular region). This explains why bone tumors occur more frequently during puberty. They grow infiltratively (invading/displacing), crossing anatomical boundary layers. Secondary bone tumors also grow infiltratively, but usually do not cross boundaries.

Giant cell tumor may occur multifocally (tumor spread across multiple tumor nests), although this is rarely seen (approximately 0.04-1% of bone tumors). It is then frequently associated with Paget’s disease (disease of the skeletal system with bone remodeling). In this case, the giant cell tumor is usually localized in the skull or ischium (lat. Os ischii or ischium for short). A multifocal giant cell tumor without Paget’s disease is mainly found in the bones of the hand.

Sex ratio: Women are slightly more frequently affected than men.

Peak incidence: Giant cell tumor occurs after closure of the epiphyseal fossa (growth plate), predominantly between the ages of 20 and 40.

Giant cell tumor accounts for 5% of all primary bone tumors.

The incidence (frequency of new cases) is approximately 9 cases per 1,000,000 inhabitants per year (in Germany).

The course and prognosis depend on the location and extent of the giant cell tumor. It grows slowly, but can be locally aggressive, i.e. displacing and destructive (destruction of bone structure). In a few cases (1-2%), the giant cell tumor metastasizes (forms daughter tumors), especially to the lungs. The metastasis rate is 2-10% for a giant cell tumor in the extremities and 14% for a tumor in the spine and sacrum (lat. Os sacrum, sacrum). Lung metastases may regress spontaneously. The giant cell tumor can degenerate into a sarcoma (< 1 %). However, this usually occurs only after multiple local recurrences (recurrence of disease (recurrence) at the same site).Giant cell tumor is associated with a high risk of recurrence (15% in the extremities). The local recurrence rate of giant cell tumor in the spine and sacrum (sacral bone) is 20-40%. If a giant cell tumor recurs, the risk of pulmonary metastases (lung metastases) is increased 6-fold.

Because of metastasis occurring in rare cases and the risk of degeneration, giant cell tumor used to be called semimalignant (= destructive, invasive growth, but rarely metastasis).