Giant cell tumor of the bone (GCTOB), also known as osteoclastoma, is a relatively uncommon tumor of the bone. It is characterized by the presence of multinucleated giant cells (osteoclast-like cells). It typically arises from the metaphysis of long bones, extends into the epiphysis adjacent to the joint surface, and has a narrow zone of transition. Although giant cell tumors are not cancerous, they are aggressive and can destroy the surrounding bone.