The term ''central giant cell reparative granuloma'' is a controversially termed lesion, as it implies a lesion arising as a response to injury. The conspicuous fact that this lesion arises in the absence of trauma, does not histologically resemble reparative tissue, is a purposeless growth, and shows progressive growth at the expense of the host argues persuasively that this lesion is a neoplasm. The term ''giant cell lesion'' avoids the controversy. The giant cell lesion may not be as aggressive as its extragnathic counterpart, perhaps partially accounted for by earlier discovery and treatment. The clinical features, radiographic characteristics, and behavior of this lesion are well known. The approximate rule of two-thirds is useful: two-thirds of patients are female, two-thirds are under the age of thirty, and two-thirds of the lesions occur in the mandible. Smaller lesions do not penetrate the cortex, but as the lesion expands, the cortical plate is eroded and the expanding mass is then covered by a thin shell of reactive bone. The lesion may not cause pain until it reaches a large size. It is not possible to recognize giant cell granuloma on radiographs alone, but clues are evident: the lesions do not form a calcified product, so are always radiolucent. When small they are unilocular but as they enlarge, scalloping at the tumor-host interface may create a sense of multi-locularity but seldom to the extent seen in lesions with which it may be confused, such as ameloblastoma. Teeth may be displaced, and roots frequently are resorbed.
Histologically, this lesion consists of a proliferation of mononuclear stromal cells, putative fibroblasts, and macrophages. Varying numbers of multi-nucleated giant cells are gathered in clusters or scattered evenly throughout the stromal cells. As many as 20 nuclei may be present in one giant cell. One-third of giant cell granulomas show osteoid formation but mineralization is insufficient to appear on radiographs. It is clear the giant cells are osteoclasts. They label with monoclonal antibodies to human osteoclasts (13C2 and 23C6) and show the same immunohisto-chemical profile as their extragnathic counterpart. Furthermore, the giant cells excavate bone, a property that is abolished by calcitonin. The old name of osteoclas-toma may be an appropriate term. There is a histologic overlap of giant cell granuloma with cherubism and brown tumor of hyperparathyroidism. The treatment for this lesion is ordinarily by vigorous curettage, a procedure complicated by the presence of teeth. The recurrence rate is approximately 20%. Resection is reserved for those too large to curette. Subcutaneous injection of calcitonin has been reported to be successful in the management of giant cell lesions of the jaws and may be an alternative to surgery, especially for large lesions.
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