Differential Diagnostic Points in Giant Cell Lesions

Distinguishing between the various types of bone lesions that contain multinucleated giant cells is of great practical importance because appropriate treatment depends upon diagnostic accuracy. Neoplastic or tumor-like destructive lesions of bone such as giant cell tumor, chondroblastoma, and aneurysmal bone cyst often require aggressive therapy. Giant cell reparative lesions, which may mimic giant cell tumors histologically, may also be locally aggressive, but they often require comparatively little therapy. Space-occupying bone lesions caused by hyperparathy-roidism (“brown tumors”) should be avoided surgically and the cause of hyperparathyroidism corrected. When developmentally self-limited lesions of bone containing giant cells such as fibrous cortical defect (non-ossifying fibroma) are examined via biopsy, they may cause histologic confusion with giant cell tumors if the radiographs are not reviewed. Their accurate differentiation is possible only if adjunctive clinical, radiographic, and biochemical data are known. Selective illustrations and a diagnostic algorithm are provided.