Radiologic findings demonstrate the lesion is most often eccentrically placed to the long axis of the bone. The center is most radiolucent with increasing density towards the periphery. There is a well-defined in defect in the metaphysis and epiphysis, with destruction of the medullary cavity and adjacent cortex. The destruction may stop just short of the joint. Intact borders and a sharp inner margin may be associated with a better prognosis. These tumors often thin the cortex, and may expand into the soft tissues surrounding the bone,or they may expand the the bone extensively, remaining within an eggshell-thin rim of periosteal new bone.
The gross appearance of the giant cell tumor is pain and, firm, and homogeneous, with foci of hemorrhage or necrosis. Microscopically, there are numerous multinucleated giant cells. The stromal cells are homogeneous mononuclear cells with around or ovoid shapes, large nuclei and indistinct nucleoli. The nuclei of the stromal cells are identical to the nuclei in the giant cells, a feature that distinguishes giant cell tumors from other lesions that also contained giant cells. Another feature of giant cell tumor is that the giant cells may contain very large numbers of nuclei, often several hundred. In some tumors, the giant cells can be seen to be engulfing more nuclei from the stroma.
Treatment of giant cell tumors is by surgery only. Intralesional excision by "extended" curettage is the treatment of choice. Curettage alone is associated with a high recurrence rate, and this can be decreased with the addition of chemical cautery using phenol, multiple freeze-thaw cycles using liquid nitrogen, and treating the walls of the cavity with a high-speed rotary burr. Local recurrence after curettage alone is thought to lead to recurrence in 50% of cases. Recurrence after extended curettage is approximately 10 percent.
The tumor cavity may be filled with polymethyl methacrylate cement or bone graft, according to the surgeon's preference. Some believe that the polymethyl methacrylate cement lowers the risk of a local recurrence due to the large amount of heat given off during hardening. Recurrences are normally treated with a second interlesional surgery. Bone graft may allow for more favorable biomechanics of load inthe nearby joint. The early signs of local recurrence may be more difficult to detect in cases treated with bone graft.
Lesions that are highly expansile and destructive, or lesions that occur in "expendable" bones such as the proximal fibula (shown here) may be excised with a wide margin. Multiply recurrent giant cell tumors are also treated with wide resection. Giant cell tumor may occur in the sacrum, a site where complete surgical excision is very difficult. Intralesional removal of as much of the lesion as possible followed by radiation to the tumor site has been associated with acceptable tumor control. There is concern about secondary malignancy arising in irradiated giant cell tumors. A variety of reconstructive methods are utilized depending on the extent of bony defect, or no reconstruction may be necessary. Chemotherapy is not used.