Giant cell tumor accounts for 5 to 9 percent of all primary bony tumors
and may be the most common bone tumor in the young adults aged 25 to 40. Giant cell tumor is are found more commonly
in women than men, and occur most often during the third decade (1). Giant cell tumors are usually found in the long
bones, most often the distal femur, proximal tibia, and distal radius. Giant cell tumor is a one of the most common
primary bone lesions in the distal phalanx. Whether that tumor arises in the epiphysis or distal metaphysis is a
matter of controversy, but giant cell tumors only occur after the epiphyseal plates have closed and a diagnosisof GCT
in a patient with open growth plates should be questioned.
Most
patients present with slowly progressive pain, with or without a mass. Symptoms arise when the lesion begins to
destroy the cortex and irritate the periosteum or when the weakening of the bone caused by the tumor causes pain due
to imminent pathologic fracture. Some giant cell tumors present with a pathologic fracture.
Giant
cell tumor of bone is a benign lesion that is a usually solitary and locally aggressive. It is believed by some to be
potentially malignant. In the very rare instances this lesion has the potential for metastasis to the lungs and in
these cases the lung lesions may behave in an indolent fashioned and even require no treatment. The authors recommend
a chest CT scan for all patients newly diagnosed with GCT.
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.
Following
surgery, patients should be made aware of the ongoing risk of local recurrence. Patients should be followed on a
regular basis for the first 2 years at least. Local recurrence of giant cell tumor should trigger a complete workup
including CT scan of the chest, abdomen and pelvis.
References:
Gielis: GCT
Huvos
Orthopedic Pathology
Bullough Orthopedic
Pathology
Adapted, with permission from bonetumor.com By Henry DeGroot III, M.D.
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