Giant Cell Tumor (Osteoclastoma)

Excerpt

Giant cell tumor (GCT) is one of the most common benign bone tumors, predominantly occurring in young adults aged 20 to 40 with a high recurrence rate and the potential for aggressive behavior. Typically found at the metaphyseal or epiphyseal regions of the tibia or femur, GCT, despite its predominantly benign nature, exhibits a highly unpredictable spectrum of disease behavior. Local aggressiveness varies from focal symptoms arising from bony or cortical destruction and surrounding soft tissue expansion to the rare occurrence of metastasis. Instances of GCT within the axial skeleton pose a heightened risk of severe local complications and are often deemed unresectable.

Under the microscope, the biopsied tissue reveals multinucleated giant cells comprising 3 distinct cell types:

1. Giant cell tumor stromal cells originating from osteoblasts

2. Mononuclear histiocytic cells

3. Multinucleated giant cells belonging to an osteoclast-monocyte lineage

The giant cells carry out the primary task of tumor bone resorption within the tumor. The spindle-like stromal cells are pivotal in recruiting monocytes and facilitating their fusion into giant cells. The stromal cells also improve the resorptive capabilities of the giant cells, contributing to the overall bone resorption mechanism.