Giant Cell Tumor (GCT) of Bone

This is a large expansile mass extending to and involving the epiphysis up to the subchondral region.
No definite periosteal reaction is identified.
No sclerotic rim is present but the mass appears well-defined.
This radiolucent lesion in a patient with closed epiphyses is most suggestive of a giant cell tumor.
The lateral view confirms the location and extent of the mass.

Crucial history, not initially provided, is that this lesion is actually a recurrence of the patient's original Giant Cell Tumor, re-appearing after treatment with curettage and bone packing.
- Without this history, the question of calcium or new bone formation would immediately raise the question of osteogenic sarcoma in a patient, age 15.
Recurrence of the original lesion after curettage is a well-known complication of this Rx.

There are several facts regarding Giant Cell Tumors you may wish to review.

Usually discovered between 20 and 40 (75%).
M=F. ? more common in Chinese
an association with Paget's disease is frequently quoted.
50-65% occur around the knee.
- radius, humerus also common.
- Spine (esp. sacrum), ilia, less commonly involved.
In long tubular bones, the diagnosis of GCT is made by finding:
- an eccentric, lytic lesion
- extending to the subchondral region
- in a patient with closed epiphyses
- with minimal or absent periosteal reaction
- and almost always absent sclerotic rim
Often recurs after curretage/resection.
Up to 15% can be malignant.
- Mets to lung occur even with "benign" tumors.
DDX:
- Aneurysmal Bone Cyst
- Brown tumor of HPTH
- Fibrous Dysplasia
- Eosinophilic granuloma
- Giant Cell reparative granuloma

refs:: Resnick, D., Bone and Joint Imaging, W.B. Saunders, Philadelphia, PA, 1989, pp. 1148-1153.; Greenfield, G.B., Radiology of Bone Diseases, 4th ed., J.B. Lippincott, Philadelphia, PA, 1986, pp. 605-618.