Either on radiographs or on the histology slide, it is often very difficult to diffrentiate agressive, so called malignant giant cell tumor, especially those that makes new bones within the tumor, from other giant cell-rich sarcoma. We reviewed our nine cases of malignant giant cell tumor. All were young adult ranged from sixteen to twenty eight year old, and seven were females. Affected sites were proximal tibia in four, distal radius in two, distal femur in one, pubic bone in one, and proximal fibula in one. On plain radiographs, eight cases out of nine showed purely osteolytic and infiltrative pattern,
which was quite different from the typical soap-bubble, ballooning appearance of classic giant cell tumor. Wide resection was done in six cases, which were reconstructed with tumor prosthesis in four, with vascularized fibular graft in one, and with reconstruction of soft tissue only in one. Contaminated marginal excision was done in one case, but secondary amputation was inevitable due to extensive local recurrence. Intralesional curettage was performed in two cases, both of which recurred in a few months. These two patients died of systemic metastasis and the diagnosis of these two was changed to giant cell-rich sarcoma. Local recurrence developed in all three cases with intralesional or contaminated margin, whereas only one local recurrence in six cases with wide margin. In summary, two cases out of nine agrressive, so-called malignant giant cell tumor were proved clinnically as giant cell-rich osteosarcoma, and only one lung metastasis developed among seven cases of aggressive malignant giant cell tumor. Therefore, the possibility of giant cell-rich sarcoma shoud be kept in mind when aggressive giant cell tumor showed purely osteolytic and infiltrative pattern on plain radiographs. Wide surgical margin has to be obtained by any treatment modalities to minimize recurrence.
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